












COPYRIGHT DEPOSIT. 








































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GUARANTY BUILDING (NOW CALLED PRUDENTIAL BUILDING), BUFFALO, N. Y. 

* Adler & Sullivan, Architects. 

For Detail of Lower Portion, See Opposite Page. 

Reproduced by Courtesy of the Northwestern Terra-Cotta Company. 


'•€.1 



















Steel Construction 


A Practical Treatise on the 

MODERN USE OF STEEL IN THE ERECTION OF FIREPROOF BUILDINGS, 
AND ITS APPLICATIONS TO STRUCTURAL WORK 
IN GENERAL 


By EDWARD A. TUCKER, S.B. 

J - I 

Architectural Engineer. Member of American Society of 
Civil Engineers 


ILLUSTRATED 



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» 




CHICAGO 

AMERICAN SCHOOL OF CORRESPONDENCE 
1910 













4 


Ap^ / ^ 
■*> ^ 


Copyright 1910 by 

American School of Correspondence 


Entered at Stationers’ Hall, London 
All Rights Reserved 




CGI.A261351 





2.3- 


Foreword 


N recent, years, such marvelous advances have been 
made in the engineering and scientific fields, and 
so rapid has been the evolution of mechanical and 
constructive processes and methods, that a distinct 
need has been created for a series of practical 
working guides , of convenient size and low cost, embodying the 
accumulated results of experience and the most approved modern 
practice along a great variety of lines. To fill this acknowledged 
need, is the special purpose of the series of handbooks to which 
this volume belongs. 

<L In the preparation of this series, it has been the aim of the pub¬ 
lishers to lay special stress on the practiced side of each subject, 
as distinguished from mere theoretical or academic discussion. 
Each volume is written by a well-known expert of acknowledged 
authority in his special line, and is based on a most careful study 
of practical needs and up-to-date methods as developed under the • 
conditions of actual practice in the field, the shop, the mill, the 
power house, the drafting room, the engine room, etc. 

C. These volumes are especially adapted for purposes of self- 
instruction and home study. The utmost care has been used to 
bring the treatment of each subject within the range of the com- 




mon understanding, so that the work will appeal not only to the 
technically trained expert, but also to the beginner and the self- 
taught practical man who wishes to keep abreast of modern 
progress. The language is simple and clear; heavy technical terms 
and the formulae of the higher' mathematics have been avoided, 
yet without sacrificing any of the requirements of practical 
instruction; the arrangement of matter is such as to carry the 
reader along by easy steps to complete mastery of each subject; 
frequent examples for practice are given, to enable the reader to 
test his knowledge and make it a permanent possession; and the 
illustrations are selected with the greatest care to supplement and 
make clear the references in the text. 

CL The method adopted in the preparation of these volumes is that 
which the American School of Correspondence has developed and 
employed so successfully for many years. It is not an experiment, 
but has stood the severest of all tests—that of practical use—which 
has demonstrated it to be the best method yet devised for the 
education of the busy working man. 

€1 For purposes of ready reference and timely information when 
needed, it is believed that this series of handbooks will be found to 
meet every requirement. 





Table of Contents 


« 


Structural Elements of a Building .Page 3 

oundations Enclosing Walls (Load-Bearing, Self-Supporting, Cur¬ 
tain, Metal, Concrete)—Columns and Bearing Partitions—Floors 
(Arches, Beams, Girders)—Roof. . • 


Steel Shapes and Fireproof Construction .... Page 9 

Method of Rolling Steel Shapes—Beams (I-Beams, Tees, Zees) — 
Channels—Angles—Plates (Sheared, Universal Mill or Edged)—Uses 
of Various Sections—Rules for Ordering—Use of Handbooks and 
1 ables Safe Loads—Lateral and Vertical Deflection—Spacing of 
Beams Deflection of Beams—Properties of I-Beams, Trough Plates, 
Corrugated Plates, Channels, Standard and Special Angles—Build¬ 
ing Laws of Different Cities—Wind-Pressure—Layout of Steel Frame 
Position of Columns, Beams, and Girders—Tie-Rods—Fireproof and 
Fire-Resisting Materials—Terra-Cotta Floor and Roof Arches—Guas- 
tavino Arch—Concrete-Steel Floor and Roof Arches—Weights of and 
Safe Loads for Hollow-Tile Arches—Weights of Various Floor and 
Roof Materials—Choice of System—Partitions—Column Coverings— 
Corrosion of Steel—Paints—Fire-Resisting Woods. 


Calculation of Shapes .. . - Page 91 

Beams and Girders (Determination and Distribution of Loads) — 
Weights of Various Materials of Construction—Lintels—Beam-Plates 
—Anchors—Separators—Columns—Effect of Column Connections— 
Column Diagrams and Tables—Cast-Iron, Concrete, and Steel Columns 
—Trusses—Bracing—Design of Trusses (Selection of Type, Deter¬ 
mination of Load, Roof-Pressures). 


Frame Connections and Details. Page 126 

Connections of Beams to Girders and Columns—Column Caps, Bases, 
and Splices—Roof Details—Inspection—Relations of Engineer and 
Architect—Interpretation of Drawings and Specifications—Shop Prac¬ 
tice and Use of Shop Drawings—Standard Forms—Mill or Shop In¬ 
voices—Estimating—Effect of Changes—Foundation (Spread, Caisson, 
Pile)—Improvement of Bearing Power—Grillage Foundations—Can¬ 
tilever Foundations—Retaining Walls—Underpinning, Shoring, and 
Sheath Piling—High Building Construction—Types of High Buildings 
—Foundations—Wind-Pressure—Mill Building. 


General Applications . . ..Page 181 

Abbreviations and Definitions of Terms—Details in Shop Drawings— 
Scale of Details—Rivets and Rivet-Ploles—Conventional Signs—Shear¬ 
ing and Bearing Value of Rivets—Standard Connections—Detailing 
from Framing Plan—Column Details (Base, Cap, Shaft)—Mill Build¬ 
ing Columns—Riveted Girders—Allowable Values for Girders—Pro¬ 
portions of Web—Use of Stiffeners—Cutting Off Flange Plate—Spac¬ 
ing Flange Rivets—Flange and Web Splices—Shop Details of Girders 
—Standards in Detailing Trusses—Stress in Verticals and Diagonals—• 
Choice of Sections—Trussed Stringers. 


Index . 


. Page 303 






WANAMAKER BUILDING IN NEW YORK CITY, 

D. H. Burnham & Co., Architects 
Steel and Tile Construction Throughout 























STEEL CONSTRUCTION 


PART I. 


THE STRUCTURAL ELEMENTS OF A BUILDING. 

From the structural point of view, a building consists of the 
following parts: 

1. The foundations. 

2. The enclosing walls. 

3. The columns and bearing partitions. 

4. The floors. 

5. The roof. 

If the building is very narrow, columns and bearing parti¬ 
tions may not be used, but the other four components are always 
present. Steel enters into the composition of the last four named 
parts to a greater or less extent in nearly every building, and 
these steel members are collectively called the framework of the 
building. Leaving the discussion of the subject of foundations 
until later, we shall consider briefly the component parts of the 
other divisions that may be said to constitute the elements of a 
building. 


THE ENCLOSING WALLS. 

Exterior walls, in general, are of five kinds: 

1. Masonry walls of brick or stone, supporting their own weight and 
the adjacent floor and roof loads. 

2. Masonry walls supporting their own weight, but no floor or roof 
loads. 

3. Masonry walls not self-supporting. 

4. Walls of iron, copper or other metal. 

5. Walls of concrete. 

Load-bearing Walls. Walls of the first class will be readily 
understood as regards their general characteristics, and will be 
treated more in detail under the heading “Building Laws and 
Specifications.” 


1 



4 


STEEL CON STRIPCTI ON 




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Fig / 


Self-supporting Walls, Walls of the second class are gen¬ 
erally of brick or stone, and have contained in them steel elements 
carrying the floor and roof loads. These elements consist of verti¬ 
cal members spaced at intervals in the 
wall and called the wall columns, and, 
between them, horizontal members, 
generally at the floor levels and also 
over all openings. These members at 
the floor levels are called the wall 
girders; and those over the openings, 
the lintels. The wall girders carry the 
floor and roof loads to the columns, and 
so to the foundations. The lintels, in 
this class of wall, rest on the masonry 
and sometimes are omitted entirely, 
depending on the necessity of supporting the stone lintels, 
on the impracticability of turning brick arches, or on the neces¬ 
sity of relieving such, arches of 
part of the load. kJU - 

Fig. 1 shows a construction 
of this type. The particular form 
of section of the wall girders and 
of the lintels varies, of course, with 
the conditions ; but the essential 
feature to be noted is that all loads 
are kept off the walls, except the 
weight of the masonry itself. 

Curtain Walls. Walls of the 
third class differ from the pre¬ 
ceding in that they themselves 
must be supported on the steel 
framework. The walls themselves 
may consist of brick, or of brick 
with stone or terra cotta trimmings 

or facings The steel elements sfCTO/v 

are the wall columns and wall IHROUGH WALL THROUGH FLOOR. 
girders, as before, and the horizontal members over the openings. 
These latter, instead of being called lintels, however, are called 







































































fcTEEL CONSTRUCTION 


5 


spandrel beams, since, instead of simply spanning the opening, 
they take all the load of the wall between the wall girders and 
the head of the opening, and carry this load to the columns. 
The wall girders, too, besides the floor load, generally carry the 
load of the wall for the story above. In some cases this wall 
is carried through several stories to heavy girders below, but 
such construction is not common. 

In buildings where this class of wall is used, the framework, 
in addition to carrying the loads, 
must furnish a portion of the 
lateral stiffness to resist wind 
and other strains. This feature 
will be more particularly dis¬ 
cussed under “ High-Building 
Construction.” 

Figs. 2 and 3 show types of 
construction in this class. 

Metal Walls. Walls of 
the fourth class are not com¬ 
monly met with in what is 
termed fireproof construction, 
but are more generally used in 
buildings having their floors and 
roofs framed in whole or in part 
with wood. When they do 
occur, however,* they come, 
structural^, into the previous 
class, as far as the elements of 
the framework necessary for the 
support of the floor and roof 
loads and their own weight are 
concerned. 

The chief difference is in adapting the spandrel beams to the 
support of the particular covering used. Fig. 4 illustrates such 
construction. As before, the section of the wall girders varies in 
each case with the conditions, and the spandrel section varies even 
more. 

In both of the two classes just described (curtain walls and 



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6 


STEEL CONSTRUCTION 


metal walls), no form of construction can be' called standard. 
The only principle which the student should observe and follow is 

that the wall girders and spandrel 
beams must be so arranged and 
designed as to carry properly all floor 
and roof loads, to support and carry 
properly each part of the wall itself, 
and, further, to provide necessary 
stiffness to the building. 

Concrete Walls. Walls of the 
fifth class are rarely met with at 
present, except in mills or manufac¬ 
turing plants, and discussion of their 
features is accordingly reserved for 
the discussion on “ Mill Buildings.” 

AND BEARING PARTITIONS. 

These are classed together because, either jointly or sepa¬ 
rately, they serve to carry to the foundations the portion of the 
loads not carried by the wall columns and exterior walls. When 
a partition takes these loads, it is invariably of brick. When par¬ 
titions are of other materials, they are never designed to carry 
loads, but, on the contrary, form part of the load carried by the 
floors.* 

The different forms of partitions that arg not load-bearing 
will be considered under 44 Fireproofing.” 

Columns are the more common, and in general the exclusive, 
element of the framework that carries the loads within the walls 
to the foundations. There are two features to be considered in 
connection with them: (1) the load-bearing or metal shaft, and 

(2) its covering or casing. There are a variety of sections of 
columns, some of which are illustrated by Plate I. As in the 
case of forms of spandrel beams, no definite rule can be given for 
tlie use of any particular section to the exclusion of others. These 
will be described in detail under the heading 44 Columns.” 

* Note.—T his statement refers to fireproof buildings only, and not to 
those framed with wood. 



INTERIOR COLUMNS 














































STEEL CONSTRUCTION 


7 




















































8 


STEEL CONSTRUCTION 


THE FLOORS. 

The elements of the floor are: 

1. The arch, which receives the load directly. 

2. The beams, between which the arch springs. 

3. The girders, carrying the beams. 

4. The ceiling. 

Arches. There are several different kinds of floor arch. Tn 
general, as to material of construction, they may be said to com¬ 
prise the following types: brick, corrugated iron, porous terra 
cotta, hard tile, concrete, and concrete steel. 

In office buildings and nearly all structures with a finished 
interior, some form of flat arch is used almost exclusively in order 
to avoid the necessity of furring down for a flat ceiling. In ware¬ 
houses, stores, and other buildings carrying heavy loads, seg¬ 
mental arch construction is more frequent. All segmental arch 
constructions require tie rods passing through the webs of the 
beams at intervals of about five feet, to take the thrust of the 
arches. Tie rods are also required in flat arch construction, 
where the arch is made of separate blocks, but they are not gen¬ 
erally used for flat arches of concrete slabs. 

The subject of arches will be considered in detail under 
“ Fireproofing.” 

Beams and Girders. All of the horizontal members that 
form the framing of the floor come under one or the other of these 
heads. 

A beam carries no other element of the framework, and 
receives strictly the load of the arch or the partition or other por¬ 
tion of the structure which it is designed to carry. 

A girder carries the end of one or more beams. It may at 
the same time receive direct load from the arch or partitions ; but 
if it carries other elements of the framework it should be referred 
to as a beam. 

Other uses of the terms “beam” and “girder” will be con¬ 
sidered later. 


THE ROOF. 

A roof is essentially the same as a floor as regards the ele¬ 
ments of construction. Its peculiar features are the pitch, open¬ 
ings for skylights, etc., support of pent houses, of tanks, etc. 



STEEL CONSTRUCTION 


9 


The pitch in almost every case where a fireproof roof is used 
is very flat, generally a minimum of | inch per foot and varying 
from that according to the requirements of the roof lines in each 
particular case. 

The beams and girders usually follow the pitches of the fin¬ 
ished surface of the roof, so that no additional grading on top of 
roof is necessary, except locally in order to form cradles around 
skylights and other obstructions, from the down-spout to the wall 
immediately back of it, and in a few places where the pitch of the 
roof necessarily changes between the bearings of beams. In gen- 



Fij. 25 Ficj.2.6 Ficj.2.7 

BEAM CHANNEL ZEE 

eral, however, the pitch of roof changes only at the ends of beams 
and girders. 

The pitching of beams and girders makes it necessary to furr 
down the ceiling, if this is to be left level, as it generally is. 
This is done by hanging from the beams a ceiling made either of 
tile or plastered wire lath on small angles or channels. See 
“Fireproofing” for illustrations of this. 

Tanks and pent houses require special framing for their sup¬ 
port, and all roof houses generally are constructed with a frame 
of light angles and tees. 

USE OF HANDBOOKS ON STEEL. 

The steel used in a building is in the form of single pieces, 
or combinations of one or more pieces,-to which the general term 
“shapes” is applied. All shapes are made by rolling out the 













10 


steel construction 


rectangular prisms or ingots that come from the bljist furnace. 
The following comprise nearly all the shapes rolled: Bars or 

Flats, Rounds, Half Rounds, 
Ovals, Flat Ovals, Plates, 
Angles, Tees, Zees, I Beams, 
Deck Beams, Channels, 
Trough Plates, Corrugated 
Plates, Buckled Plates. Il¬ 
lustrations of some of these are given in Figs. 25 to 85. 

flethod of Rolling. The processes of manufacture are prac¬ 
tically identical in all mills; and the sizes of the ditferent shapes 
are identical in all mills for nearly all sizes. Certain sizes are 
known as “standard,” because they are 
rolled constantly by all mills. Certain 
other sizes not so commonly used are 
known as “ special,” and vary some¬ 
what in the different mills. These 
distinctions will be explained in greater 
detail later on. 

The process of rolling an I beam 
is in general as follows: The ingots 
are put into what are called “soaking pits” below ground, 
which are heated by natural gas. When white hot or at just the 
right temperature, they are taken out and passed several times 
through the first set of shaping rolls. These rolls are at 
first spread nearly the depth of the ingot. They are automati¬ 
cally lowered, however, as the ingot is passed through, and so 
reduce the thickness sufficiently to enable the piece to pass 
through the next set of rolls, which give it the 
general shape of the letter I, though it still 
retains much thickness, and is only partly formed. 
After being shaped sufficiently by these rolls, the 
piece is passed to the third or finishing set of rolls, 
where the final shaping takes place. The piece, 
still very hot, is then passed on by movable tables 
to circular saws, where it is cut into certain 
lengths. Each size and weight of beam or other shape requires a 
distinct set of rolls in order that the pieces may be given exactly 




DECK BEAM 










STEEL CONSTRUCTION 


11 


the required thickness and dimensions. Therefore, only one size 
and weight is rolled at a time, and all orders that have accumu¬ 
lated since the last rolling of this size are then rolled at once. 



Fi 9 3Z 


SECTION OF CORRUGATED PLATES FOR FLOORS. 


The intervals of time that elapse between rollings of a given 
size vary considerably, being in some, cases perhaps six weeks, and 



SECTION OF TROUGH PLATES FOR FLOORS 

in other cases several months. Generally the larger sizes are 
rolled at one mill and the smaller sizes at another. 



SECTION OF BUCKLED PLATES FOR FLOORS. 


Characteristics of Shapes. Having seen in general how 
shapes are formed, the student should now become thoroughly 
familiar with the features of each. Beams and channels consist 
of a thin plate-like portion, called the “ web,” and, outstanding at 












































































































































12 


STEEL CONSTRUCTION 


each end of the web and at right angles to it, what are called 
“flanges.” A beam has the shape of a letter I and is therefore 
called an I beam. A channel is like a letter I with the flanges on 
one side of the web omitted. The connec¬ 
tion of flange to web is curved, and this 
curve is called the “ fillet ”; also, the inner 
side of a flange is beveled, and this bevel 
is in all sizes the same, viz., 16J per cent 
with the outer side of the flange. A 
curve of varying radius connects the outer 
edge with the inner side of a flange. The 
distribution of metal in the heavier sections 
of a given shape is shown by the portion 
not cross hatched in Figs. 25 to 29. It will 
be seen therefore that for a given depth, the only difference in the 
different weights is in the thickness of webs and width of flanges. 

The accompanying cuts, Fig. 

36, shows the relations, radii of 
curvature, and other data which 
are standard for all beams. 

c = .60 minimum web 
C = minimum web + inch 

s = thickness of web = t minimum * 

Cz 

Note. This applies for all channels 
and beams except 20-inch I and 24-inch I. 

For 20-inch standard I, S = .55 inch 
For 24-iucli I, S= .60 “ 

For 20-inch special I, S = .65 “ 

The slope of flanges for all beams and channels is 2 inches per foot. 

In tables V and VI, the weights printed in heavy type are those 
that are standard. The other weights are rolled by spreading the 
rolls of the standard size so as to give the required increase, and 
are known as special weights. These are not rolled so regularly, 
and are therefore in general more subject to delay in delivery. 

The two parts of an angle are called “ legs.” These are in 
one class of equal length, and in another class of unequal length. 
Notice also the fillet and curve at outer edge. The method of 
increasing the weight is shown by the full lines. It will be seen, 





t — .50 inch minimum 
t = .50 “ 

£=.60 “ “ 


















STEEL CONSTRUCTION 


13 


therefore, that for an angle with certain size of legs the effect of 
increasing weight is to change slightly the length of legs, and to 
increase the thickness. 


In case of angles, the distinction between “standard” and 
“special” applies, not to different weights and thicknesses of a 
given size as in the case of beams and channels, but to all weights 
of a given size as a whole, as will be seen from the tables on pages 
36-7. Angles vary in all cases by yL- inch in thickness between 
maximum and minimum thicknesses given in the tables. In the 
addition to the above special sizes of angles, there are certain 





Fig 39. 

SAFE ANCLE 


special shaped angles known as square root angles, cover angles, 
obtuse angles, and safe angles. These shapes are illustrated in 
Figs. 37, 38 and 39. Their uses, however, are limited to special 
classes of work. 

The square root angles are used where it is necessary to 
eliminate the fillet. The cover angles are for use in splicing so 
that the covers will fit the fillets of the angles spliced. As the 
demand for such is limited in any particular piece of work, it is 
customary to plane off a regular angle. The other shapes are for 
special uses, as will be readily understood. 

Bent plates are very commonly used in place of obtuse angles. 
None of the above can be obtained easily at the mins, and would 
be used only when it is not possible to adopt the regular shapes. 

With the above explanation the student should be able to 
understand readily the features of the other shapes by carefully 
studying the cuts. 

Plates are of two classes known as “sheared” plates and 
“ universal mill ” or “ edged ” plates. Plates up to 48 inches in 
width are in general universal mill plates. This term applies to 













14 


STEEL CONSTRUCTION 


plates whose edges as well as surfaces are rolled, thus insuring 
uniform width. Plates above 48 inches in width have their edges 
sheared, and are known as sheared plates. 

As already stated, there are various meanings of the terms 
« beam ” and “ girder,” and it is very important to understand fully 
the distinctions. The definitions previously given are applied to 
the manner of loading. 

“ Beam” is also the term applied to the shape rolled in the 
form of the letter I, in distinction from the channel, as noted in 
the preceding paragraphs. An I beam may be used in a position 
which, from the definition given, fixes it as a girder in distinction 
from a beam; and in speaking of such a case, one should say that 
the girder consists of an I beam. In ordering the material, however, 
the shape should be referred to as an I beam and not as an I girder. 

Similarly, a channel may be used in a position which, from 
the definition, would fix it as a beam. In referring to it, one 
should say that the beam consists of a channel; and in ordering 
material, it should be referred to as a channel and not as a beam. 

The beam may in some cases be made of sections riveted 
together, and, in such cases, would be referred to, in ordering, as a 
riveted girder. Frequently, also, two beams bolted together are 
used, and are then called beam girders. It will be seen, therefore, 
that there are two distinct uses of these terms, beams and girders 
— the first depending on the manner of loading, and the second 
on the particular form of section of the member used. These two 
uses should never be confounded, as serious results might follow, 
especially in ordering material. 

Uses of Sections. Each of the rolled sections has certain 
uses to which it is especially adapted, and for which it is most 
generally employed. I beams and channels are used principally 
as beams and girders to carry floors, roofs and walls. I beams are 
used to some extent also as columns, when the loads are relatively 
light. Channels are rarely used singly as columns; but they are 
used quite extensively in pairs latticed, and in combination with 
other shapes, to serve the purposes of columns. (For illustrations 
of such uses see Plate I, Page 7, showing column sections.) 

Channels are also used to some extent in pairs latticed, or 
with plates across flanges, for the chords in trusses. 




STEEL CONSTRUCTION 


15 


Angles are used most extensively in combination with other 
shapes to form columns, for members in trusses, and for the 
flanges of riveted girders. They are rarely used singly as columns 
except for light loads. As beams they are used only for very 
light loads, such as short lintels, ceilings, and roof purlins, when 
close spacing is necessary. They are used almost exclusively for 
the connections of beams and columns and of other members one 
with another, and for any position requiring a shelf for the sup¬ 
port of other work. 

The use,of the angle is more varied than that of almost all 
other shapes, and it forms an essential part of nearly all riveted 
members. 

Tees are rarely used in the construction of riveted members. 
Their principal uses are as beams of short spans and close spacing, 
where the loads are light and where a flange on each side of the 
center rib is necessary. Such instances occur in short lintels, ceil¬ 
ings, and certain cases of roofs, in skylights, pent houses and the 
like. 

Zees are used extensively in columns, four zees being con¬ 
nected by a web plate or lattice bars; also to some extent in lin¬ 
tels and light purlins. They are seldom used except where it is 
desirable to have the flanges arranged in this way, and usually 
angles or tees can be used to equal advantage with less expense. 

Plates are used as connecting members in nearly all riveted 
work, but rarely alone except as bearing surfaces on masonry, and 
in some cases as shelves built in and projecting from masonry 
walls to receive other members. 

Buckled Plates and Trough Plates are used almost exclus¬ 
ively in bridge work for floors. 

Corrugated Iron is used to a considerable extent in the sid¬ 
ing and roofs of sheds and other buildings of a more or less tem¬ 
porary nature. Formerly it was used to some extent in fireproof 
floors as illustrated in “Fireproofing.” This use, however, has 
almost entirely passed away. 

Rods and Bars are used almost exclusively as tension mem¬ 
bers, for example, in trusses or as hangers. 

Rules for Ordering. Material is never ordered simply from 
a schedule unless it is to be shipped plain, that is, merely cut to 



16 


STEEL CONSTRUCTION 


length without any shop work upon it. If there is to be any 
working of the material other than cutting to length, such as 
punching, riveting, or framing, a shop drawing is invariably 
necessary. Descriptions and uses of shop drawings will be given 
later. 

If the material is simply to be cut to length, however, a 
schedule is sufficient; and in such cases the following rules should 
be observed: 

1. Never give botli the thickness and weight per foot of a piece. 
Beams and channels are invariably ordered by the depth and weight per 
foot, as a 12-inch I beam 31£ lbs. per foot, or a 10-inch channel 15 lbs. per 
foot. 

Angles are almost invariably ordered by giving the dimensions of legs 
and the thickness, as a 6 in. X 6 in. X \ in. angle, or a 3 in. X 2| ; n. X £ in. 
angle. 

Zees are generally ordered by giving dimensions and thickness, as a 3 in. 
X 3 in. X | in. Z, or a 4 in. X 3 in. X jg in. Z. When unequal leg Z’s are 
ordered, always give flange dimensions first. 

• In ordering tees, the dimensions and weight per foot are given, because 
the stem of a tee tapers. Thus a 3 in. X 3 in. 6.6-lb. T, or a 3£ in. X 3| in. 
9.2-lb. T. Here, as in the case of a Z, give flange dimensions first. 

Plates are ordered by quoting width and thickness, as a 12 in. X \ in. 
plate. The same applies to bars and flats. 

Square and round rods are ordered by giving dimensions of the cross- 
section, as a |-in. diameter rod, or a 2 in. X 2 in. rod. 

2. All material, unless otherwise ordered, is subject to a standard 
variation in length of g inch. That is, it may be | inch over or under the 
specified length. If exact length is required, therefore, it is necessary to add 
after the specified length the word “exact.” 

3. If material is to be painted, the number of coats and kind of paint 
must be specified, as “ Paint, one coat graphite.” 

4. Full shipping directions must be given, including the name of party 
or parties to whom order is to be billed, name of consignee, nearest railroad 
station, and route over which shipment is to be made. 

5. Always avoid using special shapes and weights if time of delivery is 
any consideration, even at the expense of a little extra weight, unless special 
arrangement is made in advance as to the delivery which can surely be made. 
It is more important to avoid the delay that would hinder progress in all 
branches of the work on a building through waiting for a few pieces of steel, 
than it is to save a few pounds by the use of special shapes and weights. 

USE OF TABLES. 

Since all steel designs are dependent upon the use of the fore¬ 
going shapes, it will be seen that it is necessary to refer constantly 
to tables containing their dimensions and other characteristics called 



STEEL CONSTRUCTION 


17 


“ properties.” This term “ properties ” covers all the character¬ 
istics which determine strength, and which are illustrated by the 
tables. 

The different steel companies issue different books, but the 
properties for all standard shapes are practically the same. 

Before proceeding to a discussion of the use of. tables, a 
caution should be given for the future guidance of the student. 
There is always danger in using tables, diagrams, and formulae 
prepared by someone else. The danger is from two sources : (1) 
the information given may not be correct; and (2) the person 
using the data may, through failure to understand fully the basis 
on which they were prepared, use them where they are not applic¬ 
able. 

As regards the first point, the more authoritative the book in 
which the information is given, the greater is the probability that 
it is correct. Not everything in print, however, is reliable. 

The second point is even more important, because in the case 
of almost every table, diagram, or formula, there are certain limi¬ 
tations to its use, and certain cases to which, without a full under¬ 
standing of these limitations, it is liable to be applied incorrectly. 

From the outset the student should form the habit of investi¬ 
gating the derivation of tables and diagrams and the basis of for¬ 
mulae in order that he may use them intelligently. . The basis and 
application of the fundamental formulae can be understood without 
necessarily retracing all the steps in their derivation. There are 
many special formulae given which are simply modifications of the 
fundamental formulae adapted to special cases, and such formulae 
should never be used without tracing their derivation from the 
fundamental formulae. 

Safe Loads. Table I gives the total loads, uniformly distrib¬ 
uted, which can be safely carried by the different sections of 
beams and channels for spans varying by one foot. 

The manner in which the problem of the safe load will gener¬ 
ally come up is: 

Given a certain weight per linear foot of beam, and a certain 
span, to find the required size and weight of beam. In this case 
the total weight is obtained by multiplying the clear span by the 
weight per foot and adding the weight of the beam. As it is 



TABLE I. 

Safe Loads Uniformly Distributed for Standard and Special I-Beams and Channels, in Tons of 2,000 Pounds. 


18 


STEEL CONSTRUCTION 


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STEEL CONSTRUCTION 


19 


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Safe loads given include weight of beam. Maximum fibre stress 16,000 pounds per square inch. 




















































































20 


STEEL CONSTRUCTION 


TABLE I —(Concluded.) 


8* 

8" C 


r c 

£ be 

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6" C 

2 
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s ? 

5" C 

S'S) 

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0 







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5.5 




5.5 

S O. 

11.25 

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9.75 

31 

8 

^1 

6.5 

u « 

5.25 

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4 

& I 

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lbs . 

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lbs . 


lb ?. 


lbs . 

3 § 

lbs. 


lbs . 



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-5.2 

5 

8.61 

.42 

6.68 

.36 

4.62 

.31 

3.16 

.26 

2.02 

.21 

1.16 

.16 

G 

7.18 

.35 

5.57 

.30 

3,85 

.26 

2.63 

.22 

1.68 

.18 

.97 

.13 

7 

6.15 

.30 

4.77 

.26 

3.30 

.22 

2.26 

.19 

1.44 

.15 

.83 

.11 

8 

5.38 

.26 

4.18 

.23 

2.89 

.19 

1.98 

.16 

1.26 

.13 

.73 

.10 

9 

4.78 

.23 

3.71 

.20 

2.57 

.17 

1.76 

.14 

1.12 

.12 

.64 

.09 

10 

4.31 

.21 

3.34 

.18 

2.31 

.16 

1.58 

.13 

1.01 

.11 

.58 

.08 

11 

3.91 

.19 

3.04 

.16 

2.10 

.14 

1.44 

.12 

.92 

.10 

.53 

.07 

12 

3.59 

.18 

2.78 

.15 

1.93 

.13 

1.32 

.11 

.84 

.09 

.48 

.07 

13 

3.31 

.16 

2.57 

.14 

1.78 

.12 

1.22 

.10 

.78 

.08 

.45 

.06 

14 

3.08 

.15 

2.39 

.13 

1.65 

.11 

1.13 

.09 

.72 

.08 

.41 

.06 

15 

2.87 

.14 

2.23 

.12 

1.54 

.10 

1.05 

.09 

.67 

.07 

.39 

.05 

1 G 

2.69 

.13 

2.09 

.11 

1.44 

.10 

.99 

.08 

.63 

.07 

.36 

.05 

17 

2.53 

.12 

1.96 

.11 

1.36 

.09 

.93 

.08 

.59 

.06 

.34 

.05 

18 

2.39 

.11 

1.86 

.10 

1.28 

.09 

.88 

.07 

. .56 

.03 

.32 

.04 

19 

2.27 

.11 

1.76 

.09 

1.22 

.08 

.83 

.07 

.53 

.06 

.31 

.04 

20 

2.15 

.11 

1.67 

.09 

1.16 

.08 

.79 

.07 

.51 

.05 

.29 

.04 

21 

2.05 

.10 

1.59 

.09 

1.10 

.07 

.75 

.06 

.48 

.05 

.28 

.04 

22 

1.96 

.10 

1.52 

.08 

1.05 

.07 

.72 

.06 

.46 

.05 

.26 

.04 

23 

1.87 

.09 

1.45 

.08 

1.00 

.07 

.69 

.06 

.44 

.05 

.25 

.03 

24 

1.79 

.09 

1.39 

.08 

.96 

.06 

.66 

.05 

.42 

.04 

.24 

.03 

25 

1.72 

.08 

1.34 

.07 

.92 

.06 

.63 

.05 

.40 

.04 

.23 

.03 


Safe loads given include weight of beam. Maximum fibre stress 16,000 
lbs. per square inch. 


necessary to know the size of the beam before its weight can be 
added, this operation must first be neglected, and the size provi¬ 
sionally determined from the tables showing what sections will 
carry the superimposed load. Then add the weight of the selected 
beam, and again refer to the table to see if the capacity has been 
exceeded by the addition of the weight of the beam. If it has, a 
different section must be taken. 

It is important to note that there is in general a difference 
between the length of spans used in computing the total load 
carried and that used in the table. These tables are compiled 
from results given by the use of the regular beam formula, which 




































STEEL CONSTRUCTION 


21 


has been explained, and in this formula, the length of span is 
the length between centers of bearings. It is this length which 
should be used in referring to the tables. 

In some cases there would be practically no difference, as in 
the case of abeam framed between two steel girders. If, however, 
the beam were built into brick walls, the span used for computing 
total load would be the length between inside faces of walls, 
whereas the span used in tables would be from center to center of 
bearing plates. 

Another point to be noticed in the use of these tables is that 
they are based on the supposition that the beam is supported by 
adjacent construction against lateral deflection. As will be more 
fully noted later on, long members under compression fail by 
deflecting sideways. In order, therefore, to be able to carry the 
full load indicated in these tables, the top flange of the beam or 
channel must be held against side deflection. This may be accom¬ 
plished in a variety of ways. If the beam is in a floor or roof, the 
fireproof arches and the rods will generally provide the necessary 
support; or, if it is in a building not fireproof, the wood beams or 
the [flanking will also accomplish this. If, however, the beam was 
used in an unfinished attic, and the ceiling construction was at the 
bottom flange, leaving the rest of the beam exposed, the load must 
be reduced as indicated by the auxiliary table of proportionate 
loads. The load would also have to be reduced in the case of a 
beam carrying a wall with no cross framing at the level of the 
beam. It is, therefore, of the first importance to know exactly 
how the loads are carried by the beam, and in what relations other 
parts of the construction stand to the beam. 

In practice, spans not exceeding twenty times the flange width 
are not considered to require side support. 

In some cases there must be made still another modification 
of the loads indicated by these tables, and that is to provide against 
excessive vertical deflection. It is well known that all members 
loaded transversely will bend before they will break. In other 
words, any given load causes a certain amount of deflection. It is 
not practicable, however, to allow this deflection to be very great 
in structural members, because of the resulting vibration and be¬ 
cause where there are plastered surfaces cracks will occur. It is 




TABLE II. 

Spacing of Standard I-Beams for Uniform Load of 100 Pounds per Square Foot. Proper Distance in Feet Center to Center of Beams. 


22 


STEEL CONSTRUCTION 


HH 

CO 

5.5 

lbs. 

7.0 

4.9 

3.6 

2.8 

2.2 

1.8 

1.5 

1.2 

1.0 

0.9 

h -1 

7.5 

lbs. 

12.7 

8.8 

6.5 

. 5.0 

i 3.9 

3.2 

2.6 

2.2 

1.9 

1.6 

1.4 

1.2 

1.1 

.98 

HH 

iO 

9.75 

lbs. 

20.6 

14.3 

10.5 

8.1 

6.4 

5.2 

4.3 

3.6 

3.1 

2.6 

2.3 

2.0 

1.8 

1.6 

1.4 

1.3 

1.2 

1.1 

CO 

12.25 

lbs. 

31.0 

21.5 

15.8 

12.1 

9.6 

7.8 

6.4 

5.4 

4.6 

4.0 

3.4 

3.0 

2.7 

2.4 

2.2 

1.9 

1.8 

1.6 

HH 

i> 

15 

lbs. 

44.2 

30.7 

22.5 

17.3 

13.6 

11.1 

9.1 

7.7 

6.5 

5.6 

4.9 

4.3 

3.8 

3.4 

3.1 

2.8 

2.5 

2.3 

HH 

GO 

18 

lbs. 

60.7 

42.1 

31.0 

23.7 

18.7 

15.2 

12.5 

10.5 

9.0 

7 . 7 . 

6.7 

5.9 

5.3 

4.7 

4.2 

3.8 

3.4 

3.1 

© 

21 

lbs. 

80.5 

55.9 

41.1 

31.5 

24.9 

20.1 

16.6 

14.0 

11.9 

10.3 

9.0 

7.9 

7.0 

6.2 

5.6 

5.0 

4.6 

3.8 

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For load of 200pounds per square foot, divide the spacing given by 2. Maximum fibre stress, 16,000 pounds per square inch. 











































































TABLE II—(Concluded.) 

Spacing of Standard I-Beams for Uniform Load of 150 Pounds per Square Foot. Proper Distance in Feet Center to Center of Beams. 


STEEL CONSTRUCTION' 


23 




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For load of 300 pounds per square foot, divide the spacing given by 2. Maximum fibre stress, 16,000 pounds per square inch. 






















































































24 


STEEL CONSTRUCTION 


not sufficient, therefore, merely to get a section strong enough to 
carry the given load, it must also be stiff enough not to deflect 
more than a certain proportion of its length under this load. It 
has been determined that a beam can deflect of its length, or 
3 ^ of an inch per foot of length, without causing cracks in a plas¬ 
tered ceiling; and it is this criterion which is generally followed 
in determining the section required to meet the condition of safe 
deflection. 

In Table I the loads above the heavy black line are the safe 
loads which can be carried without exceeding the above deflection. 
A beam may be used on spans longer than those above the black 
line; but in this case, in order not to exceed the safe deflection, 
the load indicated by the tables opposite this span must be reduced 
by the following rule : 

Rule for Safe Loads above Spans Limited by Deflection. 

Divide the load given opposite the span corresponding to the length 
of beam by the corresponding span, and multiply by the span given 
just above the black line ; or, 

If S = the given span, 

L = the tabular load for this span, 

S x = the span just above the heavy black line, 

Lj — the required load, 


then L x 


S X L 

~S~* 


In cases where the depth of beam is not limited, comparison 
of different depths of beams should be made, and the one selected 
which proves the most economical. 

Spacing of Beams. In many cases where the location of 
columns and spacing of beams are not fixed by certain features 
of design or construction, the problem arises in a form for which 
a table different from Table I is more useful. For instance, 
if the problem is to space the columns and beams to give the most 
economical sections to carry the given loads, Table II will be use¬ 
ful. This gives the spacing of beams for different spans to carry 
safely a load of 100 lbs. and 150 lbs. per square foot. By com¬ 
parisons, therefore, of the different sections, spans, and spacing that 
may be used, the most economical section can be selected. 

The above table is useful also when it is desired to know the 



STEEL CONSTRUCTION 


‘25 


loading that a certain floor was designed to carry and when only 
the framing plan is at hand. 

If other loads per square foot are used, the table can be modi¬ 
fied by dividing the spacings given by the ratio of the required 
load to the indicated load of the table. The same modifications for 
lateral and vertical deflection must be made as in the preceding table. 

In all cases where there is a choice between beams of different 
depths, it should be borne in mind that beams of greater depth 
than 15 inches cost an extra one-tenth of a cent per pound; this, 
therefore, affects their relative economy. 

Deflection. As noted in preceding paragraphs, it is impor¬ 
tant to know what the vertical deflection of a shape will be under 
the loads and for the spans specified, as in the majority of cases 
the section cannot be selected from the tables of safe loads because 
of unequal loading or because some other shape is used. It is 
therefore necessary to be able to calculate from additional tables 
what the deflection will be. 

The following formula can be readily used for this purpose. 
We shall first explain its derivation. 

The general formula for the deflection of any shape supported 
at the ends and loaded uniformly is: 

,5 WZ3 
384 El* 

Where W is the total load, E the modulus of elasticity, and 

I the moment of i nerti a. 

._ - _ is a constant since E — 29,000,000 

384 E 


W == pi, and M = l pi 2 = i W l 
W l 


, M I _ 
and — — — — 


; therefore WZ — 


8 X 16,000 X I 


f y 8 X 16,000 y 

if the beam is loaded up to its full capacity, and the fibre stress is 

taken at 16,000. 

TU , , . '5Z2 X B X 16,000 X I 

1 herefore d = - — mwry - 

.000057 ol ^ or> s j nce h — depth of beam = 2y, 


y 

.000115I 2 


( 2 ). 


In this formula l must be taken in inches. 










26 


STEEL CONSTRUCTION 


From this general formula (1) a table in a number of differ¬ 
ent forms can be made. In Table III different values of l are 
substituted, so that the deflection in inches is obtained by taking 
the constant in the table corresponding to the given span, and 
dividing by the depth of the beam. 

Another table could be made by substituting different values 
of h corresponding to different beams, and this would readily give 
for each beam the deflection by multiplying by the square of the 
span in inches. 

If the fibre stress in the beam due to the loading was less than 
16,000, the deflection would be obtained by multiplying the result 
given in the table by the ratio of given fibre stress to 16,000. 

The formula (2) applies directly to beams and channels only. 
If, therefore, a table based on this formula is made, and it is desired 
to use it for determining the deflection of unsymmetrical shapes^ 
such as angles, tees, etc., the coefficients given must be divided by 
twice the distance of the neutral axis from extreme fibre, since 
both numerator and denominator of (1) has been multiplied by 2. 

If a beam had a center load, its deflection could be obtained 
from this table by multiplying by -|, this being the ratio of the 
deflection of a beam supported at the ends and loaded with a center 
load, to that of a similar beam with the same total load uniformly 
distributed. 

In the table of safe leads it will be noted that a heavy black 
line divides the capacities specified. This is to denote the limit 
of span beyond which the deflection of the beam, if loaded to its 
full capacity, would be likely to cause the ceiling to crack. This 
limit of span can be determined from the formulae given above, as 
follows : 

A deflection of g of the span can be safely allowed without 
causing cracks. Substituting gi^ for d, therefore, we have 
l __ 5Z 2 X 8 X 16,000 
360 384 E y 

and l = 48.3 y 

Making the substitutions of. the value of y for different sized 
beams, gives limits agreeing with those in the Cambria Hand Book. 
The limits given in the Carnegie book are fixed arbitrarily at 20 
times the depth of beam and some less than these. 




steel Construction 


27 


Expressing the above formula in a different form, we have 

f 7 __ 384 E y 

' ~ 360 X 5 X 8 

, - l 384 E ~ , , , N 

and/_ = —----_ = C (a constant). 

y 360 x5x8 v J 

f L = 773,333. 

y 


TABLE III. 

Coefficients for Deflection in Inches for Cambria Shapes Used as Beams Subjected 
to Safe Loads Uniformly Distributed. 


Distance 

Coefficient for 

Coefficient for 

Distance 

Coefficient for 

Coefficient for 

between 

Fibre Stress of 

Fibre Stress of 

between 

Fibre Stress of 

Fibre Stress of 

Supports 

16000 lbs. per 

12 500 lbs. per 

Supports 

16000 lbs. per 

12500 lbs. per 

in feet. 

Square Inch. 

Square Inch. 

in Feet. 

Square Inch. 

Square Inch. 

Xa 

H 

H' 

Xi 

H 

H 

4 

.265 

.207 

23 

8.756 

6.841 

5 

.414 

.323 

24 

9.534 

7.448 

6 

.596 

.466 

25 

10.345 

8.082 

7 

.811 

.634 

26 

11.189 

8.741 

8 

1.059 

.828 

27 

12.066 

9.427 

9 

1.341 

1.047 

28 

12.977 

10.138 

10 

1.655 

1.293 

29 

13.920 

10.875 

11 

2.003 

1.565 

30 

14.897 

11.638 

12 

2.383 

1.862 

31 

15.906 

12.427 

13 

2.797 

2.185 

32 

16.949 

13.241 . 

14 

3.244 

2.534 

33 

18.025 

14.082 

15 

3.724 

2.909 

34 

19.134 

14.948 

16 

4.237 

3.310 

35 

20.276 

15.841 

17 

4.783 

3.737 

36 

21.451 

16.759 ‘ 

18 

5.363 

4.190 

37 

22.659 

17.703 

19 

5.975 

4.668 

38 

23.901 

18.672 

20 

6.621 

5.172 

39 

25.175 

19.668 

21 

7.299 

5.703 

40 

26.483 

20.690 

22 

8.011 

6.259 





This equation shows that if the table of properties is used to 
determine the capacity of a beam for a certain span which will be 
within the plaster limits of deflection, the product of the fibre 
strain and the span must be kept constant for a given depth 
of beam. 

For example, if it is desired to know the fibre strain allowable 
for a 12-inch beam on an effective span of 30-0" (30 feet 0 inches) 
such that the plaster deflection will not be exceeded, we have 


773,333 X 6 
30 X 12 


12 , 888 . 



















28 


STEEL CONSTRUCTION 


The formula can be more quickly used by comparison with 
the limiting span given by the table of safe loads. In the above 
case the limit of span for a 12-inch beam and a fibre strain of 
16,000 lbs. is 24 feet; therefore the required 

/ = 24 X 16,000 
J 30 

= 12,800 

Lateral Deflection of Beams. When beams are used for long 
spans, and the construction is such that no support against side 
deflection is given, the beam will not safely carry the full load 

TABLE IV. 

Reduction in Values of Allowable Fibre Stress and Safe Loads for Shapes Used as 
Beams Due to Lateral Hexure. 


Ratio of Span 
or Distance 
between 
Lateral 
Supports to 
Flange Width. 

Allowable Unit 
Stress for Direct 
Flexure in 
Extreme Fibre. 

1 

Proportion of 

Tabular Safe 

Load to bo 

Used. 

Ratio of Span 
or Distance 
between 
Lateral 
Supports to 
Flange Width. 

Allowable Unit 
Stress for Direct 
Flexure in 
Extreme Fibro. 

Proportion of 

Tabular Safe 

Load to be 

Usad 

] 

b 

P 

1 

b 

P 

• 19.37 

16000 

1.0 

65 

7474 

.47 

20 

15882 

.97 

70 

6835 

.43 

25 

14897 

.93 

75 

6261 

.39 • 

30 

13846 

.87 

80 

5745 

.36 

35 

12781 

.80 

85 

5281 

.33 

40 

11739 

.73 

90. 

4865 

.30 

45 

10746 

.67 

95 

4595 

.29 

50 

9818 

.61 

100 

4154 

.26 

55 

8963 

.56 

105 

3850 

.24 

60 

8182 

.51 

110 

3576 

.22 


indicated by the table, and the allowable fibre stress in top flange 
must be reduced. If such a beam were to carry a load giving 
a fibre stress of 16,000 lbs. per square inch, the actual fibre stress 
in top flange would be greater than this, as the deflection sideways 
would tend to distort the top flange and thus cause the additional 
stresses. 

The length of beam which it is customary to consider capable 
of safely carrying the full calculated load without support against 
lateral deflection, is twenty times the flange width. The reason 
for thus fixing upon twenty times the flange width may be seen 
from the following: 
























STEEL CONSTRUCTION 


29 


In any consideration of a reduction of stress in a compression 
member due to bending caused by its unsupported length, it is 
customary to use Gordon’s formula for the safe stress in columns. 
This formula is : 


f = 


i + 


1'2 


For columns with fixed ends, a =36,000. Now if we consider a 
5-inch 9.75-lb. I, the moment of inertia about the neutral axis 
coincident with center line of web is 1' = 1.23. 

Since the moment of inertia of the web alone about this axis 
is inappreciable, the moment of inertia of each flange about this 
axis is V j = .62. 

The area of the whole section = 2.87 sq. in. 

Web = _M - 
Area of flanges = 2.01 sq. in. 

Area of one flange =: 1.00 “ 

Therefore r' f 2 = .62 
r' t = .79 

The width of flange for 5-in. beam = b ~ 3.00 in. 

Therefore r\ = ~^- 

Tests on full-sized columns show that columns of length less 
than ninety times the radius of gyration bend little if any under 
their load. It is, therefore, generally customary to disregard the 
effect of bending for lengths less than 90 radii. If in the above 
we multiply, we have : 

90 r' f = 23.7 b 

The assumption that with full fibre stress of 16,000 lbs. 
beams should be supported at distances not greater than twenty 
times the flange width, brings the limit under that of 90 radii. 

Approximately the same result will be obtained if we assume 
the flange a rectangle and substitute 18,000 for / in Gordan’s 


formula. 


Then r 2 = 


b 2 
12 


and/ c = 


18,000 


1 


l 2 


3,000 b 2 


and for l = 20 b 


f c = 15,900. 






30 


STEEL CONSTRUCTION 


TABLE V. 

Properties of UBeams. 


1 

2 

3 

4 

5 

6 

7 

8 

0 

1 

Section Indei 

r 

2 

P 

E* 

31 

11 

1 

l 1 

!. 

I 3 

& 

131;, 

ifK 1 

* i 

Safi* 

pjr 

m 

r 



100.00 

29.41 

0.754 

7.254 

2380.3 

48.56 

9.00 



95.00 

27.94 

0.692 

7.192 

- 2309.6 

47.10 

9.09 

B 1 

24 

90.00 

26.47 

0.631 

7.131 

2239.1 

45.70 

9.20 



85.00 

25.00 

0.570 

7.070 

2168.6 

44.35 

9.31 



80.00 

23.32 

0.500 

7.000 

2087.9 

42.86 

9.46 



100.00 

29.41 

0.884 

7.284 

1655.8 

52.65 

7.50 



95.00 

27.94 

0.810 

7.210 

1606.8 

50.78 

7.58 

B 2 

20 

90.00 

26.47 

0.737 

7.137 

1557.8 

48.98 

7.67 



85.00 

25.00 

0.663 

7.063 

1508.7 

47.25 

7.77 



80.00 

23.73 

0.600 

7.000 

1466.5 

45.81 

7.86 



75.00 

22.06 

0.649 

6.399 

1268.9 

30.25 

7.58 

B 3 

20 

70.00 

20.59 

0.575 

6.325 

1219.9 

29.04 

7.70 



65.00 

19.08 

0.500 

6.250 

1169.6 

27.86 

7.83 



70.00 

20.59 

0.719 

6.259 

921.3 

24.62 

6.69 

B80 

18 

65.00 

19.12 

0.637 

6.177 

881.5 

23.47 

6.79 ’ 



60.00 

17.65 

0.555 

6.095 

841.8 

22.38 

6.91 



55.00 

15.93 

0.460 

6.000 

795.6 

21.19 

7.07 



100.00 

29.41 

1.184 

6.774 

900.5 

50.98 

5.53 



95.00 

27.94 

1.085 

6.675 

872.9 

48.37 

5.59 

D 4 

1 o 

90.00 

26.47 

0.987 

6.577 

845.4 

45.91 

5.65 



85.00 

25.00 

0.889 

6.479 

817 8 

43.57 

5.72 



80.00 

23.81 

0.810 

6.400 

795.5 

41.76 

5.78 



75.00 

22.06 

0.8S2 

6.292 

691.2 

30.68 

5.60 

B 5 

15 

70.00 

20.59 

0.784 

6.194 

663.6 

29.00 

5.68 



65.00 

19.12 

0.686 

6.096 

636.0 

27.42 

5.77 



60.00 

17.67 

0.590 

6.000 

609.0 

25.96 

5.87 



55.00 

16.18 

0.650 

5.746 

511.0 

17.06 

5.62 

B 7 

15 

50.00 

14.71 

0.55S 

5.648 

483.4 

16.04 

5.73 



45.00 

13.24 

0.460 

5.550 

455.8 

15.00 

5.87 



42.00 

12.48 

0.410 

5.500 

441.7 

14.62 

5.95 



55.00 

16.18 

0.822 

5.612 

321.0 

17.46 

4.45 

B 8 

12 

50.00 

14.71 

0.699 

5.489 

303.3 

16.12 

4.54 



45.00 

13.24 

0.576 

5.366 

285.7 

14.89 

4.65 



40.00 

11.84 

0.460 

5.250 

268.9 

13.81 

4.77 

B 9 

12 

35.00 

10.29 

0.436 

5.086 

228.3' 

10.07 

4.71 



31.50 

9.26 

0.350 

5.000 

215.8 

9.50 

4.83 



40.00 

11.76 

0.749 

5.099 

158.7 

9.50 

3.67 

Bll 

10 

35.00 

10.29 

0.602 

4.952 

146.4 

8.52 

3.77 



80.00 

8.82 

0.455 

4.805 

134.2 

7.65 

3.90 



25.00 

7.37 

0.310 

4.660 

122.1 

6.89 

4.07 



a5.oo 

10.29 

0.732 

4.772 

111.8 

7.31 

3.29 

B13 

9 

30.00 

8.82 

0.569 

4.609 

101.9 

6.42 

3.40 



25.00 

7.35 

0.406 

4.446 

91.9 

5.65 

3.54 



21.00 

6.31 

0.290 

4.330 

84.9 

5.16 

3.67 



25.50 

7.50 

0.541 

4.271 

68.4 

4.75 

3.02 

B 15 

8 

23.00 

6.76 

0.449 

4.179 

64.5 

4.39 

3.09 



20.50 

6.03 

0.357 

4.087 

60.6 

4.07 

3.17 



18.00 

5.33 

0.270 

4.000 

56.9 

3.78 

3.27 



20.00 

5.88 

0.458 

3.868 

42.2 

3.24 

2.68 

B 17 

7 

17.50 

5.15 

0.353 

3.763 

39.2 

2.94 

2 76 



15.00 

4.42 

0.250 

3.660 

36.2 

2.67 

2.86 



17.25 

5.07 

0.475 

3.575 

26.2 

2.36 

2.27 

B 19 

6 

14.75 

4.34 

0.352 

3.452 

24.0 

2.09 

2.35 



12.25 

3.61 

0.230 

3.330 

21.8 

1.85 

2.46 



14.75 

4.34 

0.504 

3.294 

15.2 

1.70 

1.87 

B 21 

5 

12.25 

3.60 

0.357 

3.147 

13.6 

] .45 ^ 

1 94 



9.75 

2.87 

0.210 

3.000 

12.1 

1.23 

2.05 



10.50 

3.09 

0.410 

2.880 

7.1 

1.01 

1 52 

B 23 

4 

9.50 

2.79 

0.337 

2.807 

6.7 

0.93 

•1.55 



8.50 

2.50 

0.263 

2.733 

6.4 

0.85 

1 59 



7.50 

2.21 

0.190 

2.660 

6.0 

0.77 

1.64 



7.50 

2.21 

0.361 

2.521 

2.9 

0.60 

1.15 

B 77 

3 

6.50 

1.91 

0.263 

2.423 

2.7 

0.53 

1.19. 



5.50 

1.63 

0.170 

2.330 

2.5 

0.46 

1.2 3 



























STEEL CONSTRUCTION 


TABLE V—(Continued.) 

Properties of I-Beams. 


10 

11 

12 

13 . 

14 

16 

Radius of Gy¬ 
ration Neutral 
■iJLxis Coincident 
■with Center 
Line of Web 

Section Mod¬ 
ulus Neutral 
CO Axis Perpendic¬ 
ular to Web at 
Center 

Coefficient of 

Strength for 

^Fiber Stress of 

^16,000 lbs. per 

sq. in. Used 

for Buildings 

Coefficient of 

Strength for 

< '«,Fiber Stress of 

v '12,500 lbs. per 

sq. in. Used 

for Bridges 

vi M °2 

Mil?.! 

IH 

Section Indei 

1.28 

198.4 

2115800 

1653000 

17.82 


1.30 

192.5 

2052900 

1603900 

17.99 


1.31 

186.6 

1990300 

1554900 

18.21 

B 1 

1.33 

180.7 

1927600 

1505900 

18.43 


1.30 

174.0 

1866900 

1449900 

18.72 


1.34 

165.6 

1766100 

1379800 

14.76 


1.35 

160.7 

1713900 

1339000 

14.92 


1.36 

155.8 

1661600 

1298100 

15.10 

B 2 

1.37 

150.9 

1609300 

1257200 

15.80 


1.39 

140.7 

1504300 

1222100 

16.47 


1.17 

126.9 

1353500 

1057400 

14.98 


1.19 

122.0 

1301200 

1016600 

15.21 

B 3 

1.21 

117.0 

1247000 

974700 

16.47 


1.09 

•102.4 

1091900 

853000 

13.20 


1.11 

97.9 

1044800 

816200 

18.40 

r* nr* 

1.13 

93.5 

997700 

779500 

13.63 

Lj O \J 

1.16 

88.4 

943000 

730700 

13.96 


1.31 

120.1 

1280700 

1000600 

10.75 


1.32 

116.4 

1241500 

969900 

10.86 


1.32 

112.7 

1202300 

939300 

10.99 

C 4 

1.32 

109.0 

1163000 

908600 

11.13 


1.32 

100.1 

1131300 

883900 

11.25 


1.18 

92.2 

983000 

768000 

10.95 


1.19 

88.5 

943800 

737400 

11.11 

D A 

1.20 

84.8 

904600 

706700 

11.29 

o O 

1.21 

81.2 

860100 

670600 

11.49 


1.02 

68.1 

726800 

567800 

11.05 


1.04 

64.5 

687500 

537100 

11.27 

r> *7 

1.07 

60.8 

648200 

506400 

11.54 

L> / 

1.08 

68.9 

628300 

490800 

11.70 


1.04 

53.5 

570600 

445800 

8.65 


1.05 

50.6 

539200 

421300 

8.83 

D Q 

1.08 

47.6 

507900 

396800 

9.06 

fc> o 

1.08 

44.8 

478100 

373600 

9.29 


0.99 

38.0 

405800 

317000 

9.21 

a q 

1.01 

30.0 

383700 

299700 

9.45 


0.90 

31.7 

338500 

2G4500 

7.12 


0.91 

29.3 

312400 

244100 

7.32 

Dll 

0.93 

26.8 

286300 

223600 

7.57 

Dll 

0.97 

24.4 

200600 

203500 

7.91 


0.84 

24.8 

265000 

207000 

6.36 


0.85 

22.6 

241500 

188700 

7.58 

DIO 

0.88 

20.4 

217900 

170300 

6.86 

O A o 

0.90 

18.9 

201300 

167300 

7.13 


0.80 

17.1 

182500 

142600 

5.82 


0.81 

16.1 

172000 

134400 

5.96 

R 1 «=» 

0.82 

15.1 

161600 

126200 

6.12 


0.84 

14.2 

151700 

118500 

6.32 


0.74 

12.1 

128600 

100400 

5.15 


0.76 

11.2 

119400 

93300 

5.31 

B 1 7 

0.78 

10.4 

110400 

86300 

6.60 


0.68 

8.7 

93100 

72800 

4.33 


0.69 

8.0 

85300 

60600 

4.49 

B 1 9 

0.72 

7.3 

77500 

60500 

4.70 


0.63 

6.1 

64600 

50500 


• 

0.63 

5.4 

58100 

45400 


R 2 1 

0.05 

4.8 

51600 

40300 



0.57 

3.6 

38100 

29800 



0.58 

3.4 

36000 

28100 


B 23 

0.58 

3.2 

33900 

26500 


0.69 

3.0 

31800 

24900 



0.52 

1.9 

20700 

1620 

r» f * - - - 


0.52 

1.8' 

19100 

15000 


B 77 

0.53 

t 

1.7 

17600 

13800 






































32 


STEEL CONSTRUCTION 


TABLE V — (Continued.) 

Properties of Carnegie Trough Plates. 


Section Index 

Size 

Inches 

Thickness 

Inches 

Weight per Foot 

Pounds 

Area of Section 

Square Inches 

Moment of Inertia 

w Neutral Axis 

Parallel to Length 

,n Section Modulus 

■ Axis as Before 

Radius of Gyration 

Axis as Before 

M 10 

9^x3-K 

Vi 

1G.3 

4.8 

3.G8 

1.38 

0.91 

M 11 

9j*xS# 

TO 

18.0 

5.3 

4.13 

1.57 

0.91 

M 12 

9fcxS& 

H 

19.7 

5.8 

4.57 

1.77 

0.90 

M 13 



21.4 

G.3 

5.02 

1.96 

0.90’ 

M 14 

oy 2 x3x 

U 

23 2 

G.8 

5.46 

2.15 

0.90 


TABLE V—(Concluded.) 

Properties of Carnegie Corrugated Plates. 


Section Index 

Size 

Inches 

Thickness 

Inches 

Weight per Foot 
Pounds 

Area of Section 
Square Inch 

Moment of Inertia 
t-t Neutral Axis 
Parallel to Length 

(/) Section Modulus 

Axis as before 

-i Radius of Gyration 

Axis as before 

M 30 

8^x1 % 

% 

8.1 

2.4 

0.64 

0.80 

0.52 

M 31 

8Kxli 9 a 

15 

10.1 

3.0 

0.95 

1.13 

0.57 

M 32 

8^x1 s/ 8 

H 

12.0 

3.5 

1.25 

1.42 

0.62 

M 33 


Vs 

17.75 

5.2 

4.79 

3.33 

0,96 

M 34 

12i 3 s x2}‘§ 

rs 

20.71 

6.1 

5.81 

3.90 

0.98 

M 35 

ia*x2a 

Vi 

23.67 

7.0 

6.82 

4.46 

• 0.99 


Table IV gives values to use for fibre stress, and proportions 



of full tabular load to use for different 
ratios of length and width of flange. 

Tables V, VI, VII, and VIII give 
the properties of the minimum and 
maximum sizes of the different shapes. 
These tables are for use in choosing, 
sections to meet the requirements of 
design, and will be explained in detail 
in the pages that treat of design of 
members in which these shapes are used. 

These different functions can all be 
calculated quite readily, and it is import 
tant that the student should understand 
how these are obtained. For this pur¬ 
pose the functions of a 24-inch 80-lb. 
beam will be worked out. The sec* 
tion of the beam is here shown, 


BEAM SECTION 
































STEEL CONSTRUCTION 


33 


Area. 

Web = (24 — 2.284) X .50 = 10.858 

Flanges = X 3.25 X 4 = 11.323 

1.142 X .50 X 2 = 1.142 12.465 

23.323 

It will be noticed that the areas of fillets and the roundings of outer 
edges are disregarded. These closely offset each other. 


Weight per Foot. 

Since a cubic foot of steel weighs 490 lbs., the weight per 
foot of a 24-inch beam should be: 


23.323 X 12 
1,728 X 


490 = 79.331 lbs. 


Moment of Inertia About Axis 1 —1. 

I of web (taken to outside of flanges) = ^ X | X 24 3 = 576. 

I' of flange about an axis through center of gravity of each 
component element. 

Axis A A = L x 3.25 X .60 3 X 4 = .234 

Axis B B = I x 3.25 (1.142 — .60)3 = ^ 

I of flanges about axis 1 — 1 =I'-[-Ax 4c? 2 . 

Where A = area of flanges, and d — distance from center-of 
gravity of flange to axis 1 — 1, as in the above, the flanges being 
divided into two figures, the d in each case will be the distance 
from 1 — 1 to the center of gravity of that figure. 

I = 3.25 X .60 X 11.70 2 x 4 = 1,067.752 

3.25 X .271 X 11.22 2 X 4 = 443.505 1,511.548 

576. 


2,087.548 









TABLE VI. 

Properties of Channels. 


34 


STEEL CONSTRUCTION 


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C 2 

C 3 

C 4 

C 5 

C 6 

C 7 

C 8 

C 9 

C 72 

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JO J8JUO0 

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0.823 

0.803 

0.788 

0.783 

0.780 

0.794 

0.722 

0.694 

0.677 

0.678 

0.704 

0.695 

0.651 

0.620 

0.609 

0.639 

0.615 

0.585 

0.590 

0.607 

0.587 

0.567 

0.556 

0.557 

0.576 

0.583 

0.555 

0.535 

0.528 

0.546 

0.546 

0.517 

0.503 

0.517 

0.508 

0 481 

0.489 

0.463 

0.458 

0.464 

0.459 

0.443 

0.443 

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478000 

447400 

416800 

386100 

355500 

347300 

273600 

249100 

324500 

200000 

178000 

192500 

172100 

151700 

131200 

111500 

130900 

112600 

94200 

87600 

99500 

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83200 

75000 

67300 

79000 

71800 

64700 

57500 

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54300 

48100 

42000 

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220300 
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168000 
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144100 
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112200 
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110900 
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96000 

86100 

101100 

92000 

82800 

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66800 

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5.43 

5.58 
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4.09 

4.17 
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4.43 
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3.35 

3.42 

3.52 

3.66 

3.87 

3.10 . 
3.21 

3.40 

3.49 

2.77 

2.82 

2.89 

2.98 

3.11 

2.39 

2.44 

2.50 

2.59 
2.72 

2.07 

2 13 

2 21 
2~34 

1.75 

1 83 
1.95 

1.40 

1 .51 
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1.08 

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2.85 
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1.95 
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39.9 
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5.81 
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STEEL CONSTRUCTION 


35 


Moment of Inertia about Axis 2 — 2. 

Web — l\ X 24 X - 50 * “ * 250 

Flanges axis A' A' =— X .CO X 3.25 3 X 4 = 6.866 


For axis 2-2 = +3.25 X .60 X (1.623 + .25) 2 X 4 = 27.362 


Flange axis B' B' = X .542 X 3.25 3 X 4 
36 


= 2.060 


For axis 2-2 = + .542 X 1.63 X (1.08 + .25) 2 X 4 = 6 -250 _ 4 2.5 38 

42.788 

Other methods of computing the moments of inertia would 
perhaps bring a result even closer to the values given in the tables, 
which are taken from the Carnegie Handbook, although the values 
vary a little in the different books for identical sections. 

Radius of Gyration. By definition, the radius of gyra¬ 
tion is equal to the square root of the quotient of the moment 
of inertia divided by the area of the section; therefore, if r lml and 
r 2 _ 2 correspond to radii of gyration about the axes 1-1 and 2-2 
respectively, 


'2,087.548 _ 


?Vl \ 23.323 

_ ^42.538 


9.46 


r 2-2 


23.323 


= 1.35 


Section Modulus. In the calculation of stresses in beams, 
the formula used is: 


M =H; 

y 

M I 

or, — = -. 

i y 


The proper section of beam could be determined by this 
formula, using the moment of inertia, the distance from the 
neutral axis to the extreme fibre, and the allowable fibre stress. It 


is more convenient, however, to have the constant I expressed in 

y 

the tables, and this constant is called the “ Section Modulus.” 

In the above case, therefore, 


I 


2,087.548 











TABLE VII. 

Properties of Standard and Special Angles. 

Angles with Equal Legs. 


36 


STEEL CONSTRUCTION 


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q3nojqj six? ibj}H 9{1 hh1 
‘Btyauj jo jusmojq 

I s * CO GO CO QO **1* TP 05 O CO 
CiiOCiCOiOt-OOrfOO 

l'- M QD TP OJ rt* CD TP CD* Tf 00 
OCD QOGOt^t^COOlOtATj* 

35.46 

33.72 

31.92 

30.06 

28.15 
26.19 

24.16 
22.07 
19.91 
17.68 
15.39 

— int^-^xacTrLOOJrp 
O^hL-i'-OiSTtiMON 

CD 00 C'” GO tO ,r P CO 05 2 0 00 

ti rinnn 1-1 rinnn 

8.14 

7.67 

. ® 

saqauj ‘93 ub(j 
jo qosg racuj huBig 

JO J9JU9Q JO 90HBJSIQ 

^ON^OIOJOIOW^OD 

TfCOCOCO0O^C*O*O*O*r-( 

0*05 0*0* 0* 0* 0* 0* 0* 0* 05* 

1.86 

1.84 

1.82 

1.80 

1.78 

1.75 

1.73 

1.71 

1.68 

1.66 

1.64 

^0N0C*0QD0W®-0 
O 6G O iC LG ic rr T 1 rf rp CO 

THHririTrtrlrlrt tH 

1.29 

1.27 

iQ 

ssqouj 9JBnbs 
noij39g jo Bsjy 

co^OO*co-rT‘co — ooo 
L-oooB-.o*corrtnco<ot- 

0 lO »o TP CO 0* *-« O OD 00 l> 

ON’tOlrpOOB-MiflOO 
C CO t- O Tf t- r -1 Tp (- c CO 
▼-•ocDCDXt-t^ouoiroTp 

00®09N®^'1/500—< 
ClOOl^Ol'J'XMN^O 

cs 001 - £><o <d id id rj< od 

Tt* 'rft 

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to to* 

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joog jsd jqSio^ 

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10 CO* ^ 00 O ^ « CD N-* TP 
WXC 0 X 0 * 0 * 0 * 0 *T-^r-«r-i 

®®eif <S®Oi-NM» 

sassjsssiassss 

19.9 

18.5 

CO 

saqonj ‘ssgnqoiqj, 




* * 

<N 

seqouj 

9ZIS 

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OOOOCOOOOOOOaOOOXQOCD 

O GO O O O O X O O O CO 
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tro tn to 0 »o to iciio m m tn 
XXXXXXXXXXX 

to 10 EO 0 to to ic to to LO 0 

Tf TP 

X X 

TP TP 

rH 

X9paj DOIJ09S 

COOl^OCT/Xt-tOlO^PCO 

^r-^^OOOOCOO 

'g^»- l C^5C'^lO<O£>00 0g 

j’moortejM^ujcs 

CftCl 

##**«•***##* 

A 18 

A 19 





Angles marked * are special, 






































































STEEL CONSTRUCTION 


37 


TABLE VII—(Concluded.) 
Properties of Standard and Special Angles. 
Angles with Equal Legs. 


1 

2 

3 

4 

6 

6 

7 

8 

6 

10 

1 

Section Index 

Size 

Inches 

Thickness, Inches 

Weight per Foot 
Pounds 

Area of Section 

Square Inches 

Distance of Center of 
Gravity from Back of 
Flange, Inches 

Moment of Inertia, 
Neutral Axis through 
Center of Gravity 
Parallel to Flailge 

Section Modulus 

CO Neutral Axis as 

before 

-S 08 

|-3. 

' 51 s 

r 

Least Radius of 

Gyration, Neutral Axis 

•-» through Center of 

Gravity at Angle of 

i 45 Degrees to Flange3 

♦A 51 

2^x2>< 

K 

6.8 

2.00 

0.74 

0.87 

0.58 

0.60 

0.43 

*A 62 


A 

6.1 

1.78 

0.72 

0.79 

0.52 

0.67 

0.43 

*A 53 

2\i 

X 

5.3 

1.55 

0.70 

0.70 

0.45 

0.67 

0.43 

♦A 54 

2^x2^ 

TB 

4.5 

1.81 

0.68 

0.61 

0.89 

0.68 

0.14 

* A 55 

2^x2# 

X 

8.7 

1.00 

0.66 

0.51 

0.82 

0.69 

0.44 

*A101 

2 X&X 

IB 

2.8 

0.81 

0.63 

O.S9 

0.24 

0.70 

0.44 

A 56 

2 x2 

A 

5.3 

1.50 

0.66 

0.54 

0.40 

0.59 

0.39 

A 57 

2 x2 

X 

4.7 

1.36 

0.64 

0.48 

0.35 

0.59 

0.39 

A 58 

2 x2 

A 

4.0 

1.15 

0.61 

0.42 

0.30 

0.60 

0.39 

A 59 

2 x2 

x 

8.2 

0.94 

0.59 

0.35 

0.25 

0.61 

0.39 

A GO 

2 x2 

A 

2.5 

0.72 

0.57 

0.28 

0.19 

0.G2 

0.40 

A 61 

lKxiK 

A 

4.6 

1.30 

0.59 

0.85 

0.30 

0.51 

0.83 

A 62 

\y 4 x\y 4 

X 

4.0 

1.17 

0.57 

0.81 

0.26 

0.51 

0.34 

A 63 

iyxiy 

A 

3.4 

1.00 

0.55 

0.27 

0.23 

0.52 

o.at 

A 64 

\y 4 x\y 4 

% 

2.8 

0.81 

0.53 

0.23 

0.19 

0.53 

0.34 

A 65 

v/ 4 xiy 4 

A 

2.2 

0.62 

0.51 

0.18 

0.14 

0.54 

0.&5 

A 66 

VA*i% 

X 

3.4 

0.99 

0.51 

0.19 

0.19 

0.44 

0.29 

A 67 

\y 2 x\'A 

A 

2.9 

0.84 

0.49 

0.16 

0.162 

0.44 

0.29 

A 68 

1 'A*va 

% 

2.4 

0.69 

0.47 

0.14 

0.134 

0.45 

0.29 

A 69 

l'Axi'A 

A 

1.8 

0.53 

0.44 

0.11 

0.104 

0.46 

0.29 

A102 

i y 2 xiy 2 

X 

1.3 

0.86 

0.42 

0.08 

0.070 

0.46 

0.30 

A 70 

v/ 4 x\y 4 

TB 

2.4 

0.69 

0.42 

0.09 

0.109 

0.86 

0.23 

A 71 

l'Axi'A 

X 

2.0 

0.56 

0.40 

0.077 

0.091 

0.37 

0.24 

A 72 

\y 4 x\y 4 

A 

1.5 

0.43 

0.38 

0.061 

0.071 

0.38 

0.24 

A 73 


y* 

1.1 

0.30 

0.35 

0.044 

0.049 

0.38 

0.25 

A 78 

1 xl 

X 

1.5 

0.44 

0.84 

0.037 

0.056 

0.29 

0.19 

A 79 

1 xl 

A 

1.2 

0.34 

0.32 

0.030 

0.044 

0.80 

0.19 

A 80 

1 xl 

y» 

0.8 

0.24 

0.30 

0.022 

0.031 

0.31 

0.20 

•A 81 

%x X 

A 

1.0 

0.29 

0.29 

0.019 

0.033 

0.26 

0.18 

*A 82 

X* % 

% 

0.7 

0.21 

0.26 

0.014 

0.023 

0.26 

0.19 

A 83 

y 4 x X 

A 

0.9 

0.25 

0.20 

0.012 

0.024 

0.22 

0.16 

A 84 

x-X 

y» 

0.0 

0.17 

0.23 

0.009 

0.017 

0.23 

0.17 


Angles marked * are special 






















38 


STEEL CONSTRUCTION 


The section modulus about the axis 2-2 is not given in the 
tables, because the beam is rarely used in this position. It can, 
however, be readily obtained : 


S 


2 2 


42.538 

~VT~ 


= 3.55 


Coefficient of Strength. This also is. a constant 
employed to express the relations of certain values used in the 

calculation of stresses in beams. As stated before, M = —. 

y 

Also M = | pi 2 for a load uniformly distributed', where p = 
the load per linear foot, and l = the length of span in feet. As 
the value of M in the first equation is in inch-pounds, in the second 
also it must be in inch-pounds in order to equate them. 


Therefore, M 


/1 12 pi* 


8 M n 

and j 2 = pi 2 — C ; 


also, ~r~ = pi 2 = C. 

12y 

. This value of C is convenient to use, because from it the 
total load that a beam can safely carry on a given span is readily 
obtained. 


C 

L = total load — vl = —. 

c 


To derive the value of C in the case of the beam above, if we 
use/ = 16,000, which is the value for buildings, then 


C = 


8 X 16,000 X 2,087.548 


12 X 12 


= 1,855,598. 






STEEL CONSTRUCTION 


39 


If the value of I given in the table of Carnegie’s Handbook 
be used, the value of C will check with that above. 

The value of C, however, varies as much as or more than this 
in the different books, because a slight variation in I is multiplied 
to such an extent. The variation, however, is of no practical 
importance in deducing the value of L, as the variation here is 
slight. 

C', the coefficient derived by using the value of f= 12,500, 
becomes 


8 X 12,500 X 2,087.548 
0 “ 12 X 12 

= 1,449,685. 

Equal Radii of Gyration. The last column in the table 
is very useful in the designing of members that are desired to be 
equally strong against bending both in the directon of the web and 
in a direction at right angles to it, as this column gives the dis¬ 
tance apart that beams must be spaced to accomplish this result. 

Since the radius of gyration depends on the moment of inertia 
and the area of section, it follows that for a given section, the 
radius of gyration about two axes will be proportional to their 
moments of inertia about these axes. 

If d equals the distance in inches from the center of each 
beam to the neutral axis of the two, in order to obtain 1^ = I 3 . 3 
we must have I^ = I 2 _ 2 -f- A d?. 

In the above case 


I lml — I 2 _ 2 == 2,087.548 — 42.538 = 23.323 d 2 


d = 



045.01 

23.323 


= 9.35 


Therefore 


D = 2 X 9.35 = 18.70. 






TABLE VIII. 

Properties of Standard and Special Angles. 

Angles with Unequal Legs. 


40 


STEEL CONSTRUCTION 


16 

ttpnj 11015993 

< <;<; < <•< <j < <;< < <<<<<<<<<<< <<<<<•<•<<<<< <<< 

14 

CJ 

t 

** U 
o 

finTprtf 

JSW'I 

cncO®COOpO>< 5 )OOa» OOCOCOCOCOCOt~L-t~OQ r-’f iCW»OWOlf5CO<ON ^ Tf 
i- coaoaoocooacGOcoaoaD cocoooGOOoaoooGOOoouaD abcoco 

O OOOOOOOOOO 00000*000000 0000*0000 00 0 odd 

CO 

eSroij roiJoqs 

<n i«n««d 

sny 

00 OOO — ©> CO **f O O O O CO _ CO NOOOOOh^M lOONCCOOO^WMM' ©l 00 

*o *-< *-« ©$ ©* di ©$ <& c } ©5 ©i ooccooocoooooc^ooio ooccooaSoocoooooo ic 35 o 

CJ Cl Ci Z> Cl Cl 09 Ci Oi Cl CJ — r-i — — — v* — rn-ir-i — »H — — ri — 

w 

H 

eStrspj jsSuoq 
0} pjiwwj 
suy 

Q WMCO’f^i.OCOCONCOO O O 

G> 00 00 OOOOOeOOO O t—<tht— ir-**—**—< 0^0000000000 r*Hri 

o" ooodoooooo’ r-i *-I — .-J - 1 .—’ ——vi oddoddddddd r->dri 

11 

Section Moduli 

s 

oSireu jeqjoqs 

o» l»n»«d 

sriy iwjnoH 

O OOOClClClOtr-COCQ^H (^3CihOOtOOOv-<C5COCO(M M^COiOOiOON^Wlfl oo^ 

a> iScvcowoQwoo oo^c^dt-cococococo o <o eo 

oooJooooNdddd oo L-’ o’o*idid ^ odcd td t-* co co co *d o *<* rr cd cd- ’ 

10 

93usi £ jsSuoq 
0} {tn%nj 
stxy [ejir.sn 

O <£Q7?'C©rH'rf'£~Qdr- OOO QONO't^CCOO 0-<0«Nref NC5i-n O 

1> GQOWVWr^OQOC^ t^OCO^«Cit>-OCOOCOCD G (• tO rr M r-C. l>-tO Cl CO r-< C* 

f-i d’ d* oi d d* ci *-I t-i r-J cd oo* cd ©d ©i d* d* d* d’ r-<* ci d ci cd oi ci v-.’ t-I r-i vi v-i cd cd d 

a> 

Moments of Inertia 

’ I 

o3uvij J9)Joqs 
0} [anvjuj 
suy ivJ}n9H 

39.96 

45.37 
43.13 

40.82 

38.45 
35.99 
33.47 
30.86 
28.18 

25.41 
22.56 

30.75 

29.26 
27.7*3 
26.15 
24.51 

22.82 
21.07 

19.26 
17.40 

15.46 

13.47 

29.24 

27.84 

26.38 

24.89 

23.34 

21.74 

20.08 

18.37 

16.59 

14.76 

12.86- 

16.42 

15.54 

14.CO 

CO 

eSceu jsScoq 
oj 

suy i«Jin9}{ 

oj c 2 aowcpgpaigQcOr-.o ir5omcoaOi-H©*!-<N.QO ^-«oo»OpTj*i>oo^iO^’^ eo >* m 

Ci Or-<GC-3*O:0d»-yO L-dt-dc2>*~'Oaid<OCi ClXCWCOrJ'COtMGOCO d ©$ 

o' o’ 05 d »oo t»’dd d cp cd o’ «o o* id ti* cd cd ci oo oo 

Y-* r-e — 

CO 

Perpendicular Distances 
from Center of Grav¬ 
ity to Back of 
Flanges 

e3u®u 
jeqjoqg jo 
^fovgoi 

Q t-.CJN'fWOMCWQ hrfWOCOOCOr-C-.O'l' OrfWOaDlOWrHCOO^ «GO CO 

O L-CDCOCOCOCDOO*00 ^-«r-»T-*r-i0000C500 dddd*—*-«r-tT-iOOO t- CD CO 

cd ci ci d* ci ©i ci ci ci ci ci ci cicidcicicici»«i^«"< ci dci ci ci ci ci ci ci ci ci r-^r-I 1 

eSuvjg 
J33noq jo 
310*8 <>i 

O C *i< Cl C5 N >C W O CO lO N^ftMOCCmrHOO't wONWMOtCOCO^O r- CO CO 

t- C-i Ci Ci OG GO 00 00 00 l- t'- L-*— ^-OOOOC'-OO O O O O C Oi QC oO GO X t- 

O OOOOOOOOOO rirlriririri»-.riood ^ 000000000*0 r-.r-.r-. 

lO 

Area 

of Section 
Square 
Inches 

i 

Cl ONWNrHiCNOOO OOCiNrf^CrHiflCO'- .OWW5CO«OC»f:«QNN r-^ >Q C* 

O OC.rj'OOCOl-i-'OC^ pOOiTfOi'J'COWt-r-O WOOOlflOOOWOiTf r- <D r-« 

«d cicdodL-’t^cdcdoorji ci cd L-* 2 > cd o id id rr cd cd cd td cd cd id id tt* cd cd tid© 


Weight 
per Foot 
Pounds 

10 MWNCOOOOhOO CDOdrrcDCOOr-iClCCOO CCONO-»tCOCiT-»cOON Cl c*- *-• 

o ci o cd cd **t od o t-’ id o* oo u-’ id co o’ cd cd »* ci od t» id r?* ci o cd id cd rf ©i ^ 

Cl COCOCidClClClr-i r»H MM W W 6l (MW r-i n rs re WWMMCfClnrer.wr. dCICS 

CO 

Thickness 

Inches 

icb\06(w\^-i8\co to\. N ja »e*®v , *oov^»\w_WNrj. itasoo ic » \corxo\\eonww 

—Ira — r-i(-vx—irif<T\r<j-«iO\“— >1 rvX— KHVri^N —t ^\—>h 1-IT\ txXrt^eroN. 

ri re y—i 

a 

1 . Size 
Inches 

CO CO CO CO CO CO CO CO CO CO CO Tf* *r1* -Tf* rf* -rt rT rf* rf CO CO CO CO CO CO CO CO CO CO CO ■er ^ 

X KKXXKKXKXK XXXXXXXXXXX XXXXXXXXXXX XXX 

CO CO CO CD CD <D O CO CD CO CD CO CO CO CO CO CO CO CO CO CO O CO IQ >Q >Q 

r-t 

Section 

Index 

O Or-.NM'f lOCNCOO C3-<0*HC»M'rt-iOCDNOO NCOOOiHNMTfinON CO O O 
*T 10*0*01010100100*0 GOOCOCOCOCOCOCOCOCOCO CiCitDNNN{-NNf-L t'-1>- OO 

< <<<•<<;<<;<■<•< <J<J<<<J<<<<<<J <<<<<<<<<<< <<< 


Angles marked • are special. 





















































TABLE VIII — (Continued.) 

Properties of Standard and Special Angles. 

Angles with Unequal Legs. 


STEEL CONSTRUCTION 


41 


10 

T—1 

iopni uoijoag 

it. X- Y- ^ if. Sfc 

»—< co '-f »n <-o r-co<550»-«c^e0’^»oto oNoooTo*-<e>wo mooNcoc-onN 

00 QO GO 00 00 <30 COCOOOOSOiChdOiCJO CT.OiQCiOOOOCO oooooo^ — o 

^ „ C1 ^ Oi W 02 C2 C* C2 Oi 02 02 C2 

<««< <<<<<<<<<< <<<<<<<<< <<<<<<<<<J 

14 

© 

2 u 

o 

5 

siupsfl 

rr ao >o ac co toiotfjtotOLOioooo ^•f^t'etintocoo 

00 CO 00 GO 00 GO tOCCKO OOtDOO 

O O O O O O 000000000*0 0000*00000 ooooooooo 

13 

92uv[j joijoqg 
0} lenvrvj 
sixy ivujnofi 

'tLOtDNQCOl W^>C'OOt-COOOH imncTNCDOOi-'H cnoOOv-ClMtl 1 

W OII3 O iO to AO AO AO AO AO AO AO AO CO CO AC O tC AC AC AC CD CD O C j L'J cc ”*r -rr rji t* 

12 

eStrcijJoSuoq 

oi 

sixy IvJ?no}{ 

ONQCCODO CONCOGCDO^^OIM OO^CiPl CO t’flO h* CJ CO CO tO AO AO O 00 

r.HHrsr-.ci oooooooooo cocoooaococcooabao CO 00 00 00 QO 00 CC CO GO 

r.nr.rt^T^ 0*0*000 HnrHHH OOOOOOOOO 000*000000 

11 

Section Moduli 

s 

eSuvij jJjroqs 
oi ioububj 
sixy iwinojj 

AO CO O »C © -* CCCCC^NAOCiO'f Of 1CCDCDACOO^CO-^0 e20O’<<©'*‘t^©CO'"* 

Ot-COOl-CO COlOOiDCOCODDClD rj-(X) lO (M D lO Oi CO CDCOt-'COCDCOt-COaC 

Tj« 00 CO* CO* 02 oi TT rr wj» CO* CO* CO* 02 oi ci T-I Tf Tf* CO* CO* CO* oi oi oi v« CO CO* CO* ci oi oi oi n V-. 

10 

o2uv( j Jo2uoq 
oi [onwvj 
sixy [".linos} 

(DCOD^I—<N ClNCiOOMwOr-C2 Tj*C0^C5r-iC02OA0 ihOOMOCO^CRO 

CD TT C2 O CO AC AC CO 02 OOt- AC CO 02 0 t-DAOMOiriOOOt'- L- CO rr CO 02 r-i © 00 t- 

02 ci 02 02 T-< 1-1 cieioici^'riT-HT-iv-Av-* Hiv-iH<T-«HiHtT-i©*© nnnnrdHHob 

0> 

Moments of Inertia 

I 

o2uv[j Joiuoqs 

01 10JIVJ3J 

sixy iBJinon 

02 Hi iO © 02 tJ* Nt-hCIDMCODOCOO 00 AO CO N- CO AO CO f >- © « WO^Afi-f ooo 

CD CD iC ^ CO < O GO CC O O O 05 Cd- O C.t-.C2CO^’**'"7'0OO2 CO (- r- {- O Ci AC CD 

co* 02 rn 0 0 00 AC* cd ci oi ^ ci cd t-* co co* co oi ^ 0 0 ’ 00 co 0 ci 0 * 00 t- t-dd-^ 

! co 

eSirerj jeSuoq 
oi ioiiwva 
sixy iviinojj 

O^tOONN HO AC 0 CO AC AO CO coot r-HOOMCOCi'flO OQ«fcOOACi-^ACCOCO 

t-HAOCCOO 02C0ACC200^OCDr-U> t-1C Ci O CO AC CO O t- CO h O 1CC2 DN 

j> 0 * ac ac* tj* cd ac* ac* »d y#'* ^ co* cd oi co* cd co* co* ci oi oi ci v-J cd cd co* ci oi oi oi >-»* ^ 


Perpendicular Distances 
from Center of Grav¬ 
ity to Back of 
Flanges 

e2irqj 
uoiioqs jo 
qovg oj; 

1.64 
1.62 
1.60 
1.57 
1.55 
1.53 

1.79 
1.77 

1.75 

1.72 
1.70 
1.68 
1.66 
1.63 
1.61 

1.69 

i .86 

1.84 

1.82 

1.80 
1.77 

1.76 

1.73 

1.70 
1.68 

1.65 

1.63 
1.60 
1.68 

1.66 

1.64 
1.61 

1.49 

1.47 

<D 

o2u«y 
j»2uo r [ jo 
qosaoj, 

^ 02 0 b- ac co ^oiQ^ACoo^gpcD^j* © 5 C 20 N 10 WOQO ©ao*ocQHi©©^f'C 2 

riHrtOOO OCODODDCOCOao 00C0G0a0t>t>t>t>O © 00 C& 00 00 t-t-t- 

rtHr.nr.H r-iT-ii-idddddd® 000000000 <500000000 

J 

tO 

1 

Area 

of Section 
Square 
Inchos 

02 co AO-V> AC CO t^AC^-«t^02t-C>C0ACO rfTj«CO-*-'OOAC^COO tOtOCCOQOOMft 

L- 02 fc- 02 i- 02 tOWCOCOCiTfOtOCAO CO Tf* O CD h I s - CO CO ^ODCODDOCC2 

ao ac -r/rr cd cd , ©* cd ao ac rr cd od oi *d ao ao wji cd cd ci oi Ac*orr^rcooocoo 2 cd 

! 

Weight 
per Foot 
Pounds 

lO CO 02 AO GO O t-COOO<»aoe2CDO'^t^ CiACv-<t^00 00COCO02 AOCOON«DOhN 

Ot^cDTf'OirH cd — ci GO CD AC cd-02 © GO © OO U-" AC* t* 02 v-< Ci 00 OOt'-CO'fCOr-iOOi*- 

H H Hi HHH 02 02 rtrsnH Hi Hi Hi Hi Hi rariririH Hi HHririHri 

05 

Thickness 

Inches 

rSSWRStfSR SR^^-R^-RX“R 

a 

'si 

•H O 

CO S3 

-rf ^ rf rr -r cd cd cd coco od do co co co cocococoeococococo cococococococococo 

X X X X X X XXXXXXXXXX XXXXXXXXX XXXXXXXXX 

AC AC AO AC AC to lOAOAOAOiOAOAOADAOAO AOaOAOAOaOAOaOAOAO 

rH 

Section 

Index 

S88388 S5883SS8388 8fe888S§§§ 

«-« r-i Hi Hi Hi Hi -T—« rinHrinnHn riHHHC2WC2CiC2 02C2C2O2C2O2O2C2 

<<<<<;<} ■<<•<•<<'<<•<< <<<;■<<;<<;•<•< 


Angles marked * are special, 










































































TABLE VI!J—(Continued.) 

Properties of Standard and Special Angles. 

Angles with Unequal Legs. 


42 


STEEL CONSTRUCTION 


15 

xepnj notpog 

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TABLE VIII-(Concluded.) 

Properties of Standard and Special Angles, 

Angles with Unequal Legs. 


STEEL CONSTRUCTION 


43 


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44 


STEEL CONSTRUCTION 


BUILDING LAWS AND SPECIFICATIONS. 

The requirements of the Building Departments of different 
cities vary considerably as regards detail matters, but are in quite 
close agreement on points affecting the strength of structures. 

1 The following table shows the requirements of different cities 
as regards live loads : 


TABLE IX. 

Building Laws: — Specified Live Loads in Different Classes of Buildings. 

The loads specified are exclusive of weight of materials of construction. 


Class of Structure. 

New York, 
1900. 

Chicago, 

1900. 

Philadelphia, 

1903. 

Boston, 

1900. 

Load, Pounds per Square Foot. 

Dwellings, Apartment 
Houses,Hotels, and Lodg¬ 
ing Houses. 

60 

40 

70 

50 

Office Buildings—First 

Floor . 

Office Buildings — above 
First Floor. 

150 

75 

100 

100 

100 

100 

100 

100 

Schools — except Assembly 
Halls .. 

75 



80 

Assembly Halls. 

90 

100 

120 

150 

^Stores for Heavy Materi¬ 
als; Warehouses and Fac¬ 
tories; Drill Sheds . . . 

150 

ICO 

150 

250 

Roofs. 

'50 

25 

30 

25 


♦Minimum loads as above. 

Buildings used for special purposes to have loads specified accordingly. 


Table X indicates allowable unit-stresses. 












































STEEL CONSTRUCTION' 


45 


TABLE X. 


Allowable Unit-stresses for Steel and Cast Iron, as Specified by Building Laws of 

Different Cities. 

Stresses are for Medium Steel unless otherwise noted. 


V 

New York, 
1900. 

Chicago, 

1900. 

Philadelphia, 

1903. 

Boston, 

1900. 

Pounds per Square Inch. 

Extreme fibre stress- liendiny 





Rolled steel beams and 





shapes .... . . 

1G,000 

16,000 

16.000 

16,000 

Rolled steel pins, rivets 

20,000 

22,500 


22,500 

Riveted steel beams — Com- 

- 




pression. 




12,000 

Riveted steel beams — Ten- 





sion net section. 

14,000 



15,000 

Cast iron — Compression . 

16,000 

10,000 


8,000 

Cast iron—Tension. . . . 

3,000 

2,500 

3,750 

2,500 

Compression , Direct. 





Rolled steel. 

16,000 


16,250 


Cast steel. 

16,000 


16,250 


Wrought iron. 

12,000 


12,500 


Cast iron (in short blocks) . 

16,000 


17,500 


Steel pins and rivets (bear- 





ing). 

20,000 

20,000 


18,000 

Wrought-iron pins and 





rivets (bearing). 

15,000 

15,000 


15,000 

Tension , Direct. 





Rolled steel. 

16,000 

15,000 

16,250 

15,000 

Cast steel .... • . . . . 

16,000 

15,000 

16.250 


Wrought iron. 

12,000 

12,000 

12,500 

12,000 

Cast iron. 

3,000 




Shear. 





Steel web plates. 

9,000 



10.000 

Steel shop rivets and pins . 

10,000 

10,000 

10,000 

10,000 

Steel field rivets and pins . 

8,000 

10,000 

10,000 

10,000 

Steel field bolts. 

7,000 


10,000 

10,000 

Wrought-iron web plate . . 

6,000 



9,000 

Wrought-iron shop rivets 





and pins . 

7,500 

7,500 

7,500 

9,000 

Wrought-iron field rivets 





and pins. 

6,000 

7,500 

7,500 

9,000 

Wrought-iron field bolts . . 

5,500 


7,500 

9,000 

Cast iron. 

3,000 




Columns. 





Mild steel *. 

15 200-58 - 

15,000 

14,500 

12,000 


R 


i _l L 2 





13,500 R 2 


Medium steel *. 

L 

15,200-58- 

15,000 

16,250 

12,000 


R 


I 2 





1 -j- - 





11,000 R 2 


Wrought iron. 

14,000-80 - 

12,000 

12,500 

10,000 


R 


i+ L ' 2 





15,000 R 2 


Cast iron. 

11,300-30 - 

10,000 

17.500 



R 


1/2 





1 -f- - 





400 R 2 



, Reduced by Gordon’s or other approved formula; for varying ratios of length to radius 













































46 


STEEL CONSTRUCTION 


Table XI gives, in pounds per square inch, the transverse 
strength of various stone constructions, brick and concrete: 


TABLE XI. 


Transverse Strength of Stone, Brick and Concrete. 


Extreme fibre stress — Bending. 

POUNDS PER SQUARE INCH. 

Blue stone flagging 

2,200 

Granite 

1,700 

Limestone 

900 

Marble 

2,000 

Slate 

5,800 . 

Sandstone 

810 

Brick 

725 

Concrete, 1 Port, cem., 2 sand, 5 gravel 

200 

Concrete, 1 Port, cem., 3 sand, 7 gravel 

115 


Where walls are carried by the steel framing at each story, 
they are generally made 12 inches thick. 

The question of height also affects the requirements of fire 
resistance and prevention. There is considerable variation on 
these points. Table XII gives the requirements of some cities 
whose laws are explicit as to the thickness of walls and the pro¬ 
portion of loads on columns and foundations. 


TABLE XII. 

Thickness in Inches of Brick Bearing Walls. Chicago Law, 1901. 


STORIES 

BASE¬ 

MENT 

1st 

2 d 

3d 

4th 

5 th 

6 th 

7 th 

8 th 

9th 

10th 

11th 

| 12th 

One-story 

12 

12 












Two-story 

16 

12 

12 











Tliree-story 

16 

16 

12 

12 










Four-story 

20 

20 

16 

16 

12 









Five-story 

24 

20 

20 

16 

16 

16 



I 





Six-story 

24 

20 

20 

20 

16 

16 

16 






1 

Seven-story 

24 

20 

20 

20 

20 

16 

16 

16 






Eight-story 

24 

24 

24 

20 

20 

20 

16 

16 

16 





Nine-story 

28 

24 

24 

24 

20 

20 

20 

16 

16 

10 




Ten-story 

28 

28 

28 

24 

24 

24 

20 

20 

20 

16 

16 



Eleven-story 

28 

28 

28 

21 

24 

24 

20 

20 

20 

16 

10 

16 


Twelve-story 

32 

28 

28 

28 

24 

24 

24 

20 

20 

20 

16 

16 

16 


The above table applies to manufacturing and storage buildings. 













































STEEL CONSTRUCTION 


47 


TABLE XII, A. 

Thickness in Inches of Brick Bearing Walls. Philadelphia Law, 1903. 


STORIES 

1st 

2 d 

3d 

4th 

5th 

Gth 

7th 

8th 

9th 

10th 

llth 

12th 

One-story 

13 












Two*story 

13 

13 











Three-story 

18 

13 

13 










Four-story 

18 

18 

13 

13 









Five-story 

22 

18 

18 

13 

13 








Six-story 

22 

22 

18 

18 

13 

13 

» 






Se-ven-story 

26 

22 

22 

18 

18 

13 

13 






Eight-story 

26 

26 

22 

22 

18 

18 

13 

13 





Nine-story 

30 

26 

26 

22 

22 

18 

18 

13 

13 




Ten-story 

30 

30 

26 

26 

22 

22 

18 

18 

13 

13 



Eleven-story 

34 

30 

30 

26 

26 

22 

22 

18 

18 

13 

13 


Twelve-story 

34 

34 

30 

30 

26 

26 

22 

22 

18 

18 

13 

13 


The above applies to exterior and bearing walls of business, 


manufacturing and public buildings, 75 feet to 125 feet long and 
26 feet or less clear span. Hotels and tenements may have the 
3 upper stories 13 inches and following down from that in the 
sequence given above. 


TABLE XII, B. 


Safe Bearing Values in 
Tons per kq. ft. on Dif¬ 
ferent Classes of 
Masonry. 

New York, 
1900. 

Chicago, 

1901. 

Philadelphia, 

1903. 

Boston, 

1900. 

Granite (Dressed Joints) 
in Portland Cement 

— 

7 

— 

60 

Rubble Stonework in 
Lime Mortar 

5 

— 

5 

— 

Rubble Stonework in 
Cement Mortar 

10 

— 

10 

— 

Brickwork in Lime 
Mortar 

8 

61 

8 

8 

Brickwork in Cement 
Mortar 

15 

9 

15 

15 

Concrete, Portland 
Cement 

16 

4 

15 

— 

Hardwood Piles (Max¬ 
imum on Head of Pile) 

— 

25 

20 

— 


The minimum thickness of curtain walls in Chicago is 12 


inches, in Philadelphia 13 inches, and in New York 12 inches for 









































48 


STEEL CONSTRUCTION 


the upper 75 feet of wall, and 4 inches thicker for each 60 feet 
below. The New York law allows curtain walls to be built be¬ 
tween piers or steel columns and not supported on steel girders, 
provided the thickness is 12 inches for the upper 60 feet and 4 
inches thicker for each 60 feet below. 

Wind Pressure. The Philadelphia law requires 80 pounds 
per square foot to be calculated on exposed surfaces of isolated 
buildings ; on office buildings 25 pounds per square foot at the 10th 
floors, and 2* pounds less for each story below and 2| pounds more 
for each story above, up to a maximum of 35 pounds. 

The combined stress in columns resulting from direct ver¬ 
tical loads and the bending due to the above wind pressures is 
allowed to be 30 per cent above that for simply direct loading by 
the Philadelphia law, and 50 per cent by the New York law. 

In New York no allowance for wind is required if the build¬ 
ing is under 150 feet high, and this height does not exceed four 
times the average width of base. For buildings other than as above, 
30 pounds per square foot of wind pressure from the ground to the 
top is required. The overturning moment of the wind is not 
allowed to be more than 75 per cent of the moment of stability of 
the structure. 

Reduction in Live Load on Columns, Girders and Foun¬ 
dations. The Philadelphia law allows the live loads used in calcu¬ 
lation of columns, girders and foundations for all but manufacturing 
and storage buildings, to be reduced by the following formula: 

x = 100 —1 A ; 

5 

and for light manufacturing buildings, by 

* = 100 — £ A, 

5 

where x — the percentage of live load to be used, and A =± the 
area supported. 

The New York law requires the full live load of roof and top 
floor, but allows a reduction in each succeeding lower floor of 5 per 
cent until this reduction amounts to 50 per cent of the live load; 
not less than 50 per cent of the live load may be used in the cal¬ 
culations. For foundations not less than 60 per cent of the live 
load may be used. 




STEEL CONSTRUCTION 


49 


Where the laws limit the height to about 125 feet, the 
requirements as regards fire protection and prevention are - in 
general that the floors and roofs shall be constructed of steel 
beams and girders, between which shall be sprung arches of tile 
or terra cotta or brick, or approved systems of concrete and con¬ 
crete-steel. All weight-bearing metal of every description shall 
be covered with non-combustible materials, generally terra cotta 
or wire lath and cement. 

In buildings of this height the use of wood for top floors laid 
in wood screeds imbedded in concrete, and of wood for all interior 
finish, is allowed. 

Under the New York City law, buildings above sixteen stories 
are required to have their upper stories constructed entirely with¬ 
out wood, except that the so-called fireproof wood may be used 
for interior finish. The floors, however, are required to be of tile 
or mosaic or other non-combustible material, the wood top floor 
not being allowed. 

Factor of Safety. The foregoing values represent the work¬ 
ing values of unit-stresses. They are in all cases a certain percent¬ 
age of the strains under which rupture would occur. This 
percentage varies with the different classes of material and the 
different classes of structure. The quotient of the breaking strain 
divided by the allowable or safe working strain is called the “ factor 
of safety.” 

Steel and wrought iron used in ordinary building construction 
have generally a factor of safety of 4 ; timber, generally from 6 to 
8; cast iron, from 6 to 10 ; stone from 10 to 15. 

One reason for this variation in factors of safety for different 
materials is that certain materials vary more than others in their 
internal structure; and accordingly in some cases there is a greater 
likelihood than in others, of an individual piece being below the 
average strength. Other reasons are found in the varying effects 
of time. Changes in internal structure are likely to occur in the 
lapse of years; and there is the further liability that through 
ignorance or carelessness the structure may be put to uses for 
which it was never designed. 

All these conditions make it unwise from the standpoint of 
safety to use working stresses very near the breaking strains. 




50 


STEEL CONSTRUCTION 


Steel is less subject to variation than other material Timber 
has knots, shakes, dry rot, and other defects not readily discerned, 
which may greatly reduce its strength below the average. Cast 
iron has blow-holes, cracks, flaws, internal strains, and unequally 
distributed metal, which are of frequent occurrence and very 


Basement Plan 
Fig 40 

likely to escape detection. Stone has seams, crack , flaws, and a 
structure not uniform, all causing uncertainty and variations in 
the strength of individual pieces. 

THE STEEL FRAME. 

The problems to be met with in laying out the steel frame 
and designing the different elements are never twice the same but, 













STEEL CONSTRUCTION 


51 


vary with each special case. Different classes of buildings give 
rise to different problems. Some of the problems that naturally 
arise can best be explained by going in detail through the process 
of framing the office building of which plans are given in Figs. 40 
to 45. 



First Floor Plan 
Fig. 41. 


In a building of this character, and in all buildings where the 
interior arrangement is a feature, the designer of the steel frame 
must base his work on the architect’s layout. For this purpose it 
is most convenient, in making the preliminary study and provisional 
framing plans, to use tracing paper, which can be placed over the 
architect’s plans, and thus show the position of all partitions, ducts, 
etc. 

























52 


STEEL CONSTRUCTION 


Position of Columns. The first step is the location of 
columns. These should always come in partitions, unless there is 
a large hall or like arrangement in which the columns form a 
feature. The position of the columns fixes, of course, the spans of 
beams and girders. A stiffer frame will result if the beams run 


Typical Floor Plan. 

Fig. 42. 

transverse to the longest dimension of the building. The girder 
spans should also be shorter than the beam spans, as otherwise 
excessive depth of girders will be required. In general, therefore, 
the shortest spacing of columns should be in the direction of the 
longest dimension of the building. The length of this space wPl 
be limited also by the allowable depth of floor system. For an 














STEEL CONSTRUCTION 


53 


office building like the one in question, it is not desirable to use 
beams or girders over 12 inches deep, if possible to avoid it. 
With the above points in mind, we shall see what application can 
be made in this case. 



Scale Fig. 43 

O 5 10 IS 20 25 

L UftL , J --JL. 1 .. J 


Columns cannot be located by a study of one floor plan alone, 
for the arrangement of rooms may vary from floor to floor so as to 
result in columns interfering with doorways or not coming in par¬ 
titions in certain floors, though being well adapted to the condi¬ 
tions of some one floor. The natural method, therefore, is to take 
the typical floor plan, and then adapt the locations indicated 




























































54 


STEEL CONSTRUCTION' 


therein to the conditions on the other floors. Figs. 40, 41 and 
42 show respectively the basement, first floor, and typical floor 
plans of an office building; and Figs. 43, 43A, and 44 show 
respectively the framing plans of the first and second floors and 
typical floor. 

<5 



5cale Fig 43A 

Q 5 10 IS ZO 25 

I I t 

As will be seen, the lot is approximately of the same dimen¬ 
sions on each side. There is only one right angle, however, and 
one side has two very obtuse angles. The interior arrangement of 
the typical floor shows a line of offices on three sides, with corri 









































































STEEL CONSTRUCTION 


55 


dors parallel on these sides, and an interior court. The effect of 
this court is to divide the building into sections whose longest 
dimensions are parallel to the exposed walls. 

As before noted, it is an advantage for the sake of stiffness to 
have the girders run parallel with the long sides. It is further an 
advantage, and generally necessary, to have the girders of shorter 
span than the beams, and to have them come in partitions, as 
otherwise they would drop below the ceiling or necessitate a deep 
floor system. The first step, therefore, is to see whether the col¬ 
umns can be so placed as to meet all of these requirements. In 
the present instance it will be seen that in general this can be done 
by placing the columns at the intersections of office and corridor 
partitions or walls. This is, moreover, a desirable location for the 
columns, because with the thin partitions used in offices, a column 
cannot be fireproofed without exceeding the thickness of partitions, 
and it is not desirable to have a large column casing in the middle 
of a partition. 

The next point to fix is the exact position of the column cen¬ 
ter with relation to the partitions and the direction of the column 
web. The corridor side should finish flush with the corridor par¬ 
tition, leaving the necessary casing to come in the offices. There¬ 
fore the center must come a little inside of the center of the corri¬ 
dor partition, and coincident with the center of the cross partition. 
As the greatest dimension of the column is generally in the direc¬ 
tion of the web, it will be necessary to set this in less if the web 
runs parallel with the corridor partitions and with the girders. 
This is generally the best arrangement also for the framing for, in 
the upper sections of columns, the distance between the flanges of 
the. columns might not be sufficient to allow the girder to frame 
into the web, while the beams, having a smaller flange, would take 
less room. An exception to the above consideration would be the 
case of double-beam girders, as will be explained later. 

The location and position of the main interior columns having 
thus been fixed, the next thing is to locate any columns whose 
position is dependent on special features. 

In this case, the corridor arrangement along the side E F at 
the end near D E makes it necessary to place this column out of 
the line of the others. On tins account and to avoid excessive 




56 


STEEL CONSTRUCTION 


loads on the girder framing into this column, an extra column is 
put in the partition between toilet and vent at this end. 

In the exterior walls, columns of course have to be placed at 
each corner and also at the angles in the side A B C D. The other 



Typical Floor Framing. 

Scale Fi 9 44 

O 5 10 15 20 23 

i . - 1 . 1 - .= 1 

exterior columns naturally are placed at the intersections of office 
partitions with exterior walls, because here the piers in the walls 
will be the widest. The distance from the ashlar line to the cen¬ 
ter of wall columns will vary in accordance with the architectural 
details. There should never be less than four inches of masonry 

























































STEEL CONSTRUCTION 


57 


outside of the extreme corner of column, and, if possible, there 
should be more. 

Better protection is given the steel if the web is parallel with 
the face of the wall. Where the spandrel beams and lintels are 
very eccentric, however, this position results in an uneconomical 
section, since the weakest axis of the column is thus exposed to 
the greatest bending. Some designers, however, prefer to sacrifice 
economy in this regard to more efficient protection of the metal. 

The columns thus having been placed according to the arrange¬ 
ment of the typical floor plan, the next step is to see if any 
changes are necessary to suit the conditions of the floors that differ 
from this plan, namely, the basement and the first floor. From a 
glance at the plan of the first floor, it will be seen that two of the 
columns come down in the main entrance in such position as to 
obstruct the passageway. It would be possible to change the posi¬ 
tion of these columns an^ make them conform to the first floor 
partitions. The results in che floors above, however, would not be 
so good, and therefore additional columns, will be provided, sup¬ 
porting girders at the second-floor level to carry the columns above. 
A similar provision must be made for the wall column over the 
entrance. 

The position of the columns thus having been determined, 
the girders follow by joining the centers of columns. The spacing 
of the beams will be determined largely by the system of floor 
arch to be used, except that, unless entirely impossible, a beam 
should come at each column in order to give lateral stiffness to the 
frame. If a terra cotta arch is to be used, the spacing should not 
be much over six feet at the maximum, and an arrangement such 
as shown would result. If a system of concrete arches is to be 
adopted, in which spans of eight or nine feet can be safely used, 
the beams between the two lines of girders on each side of the 
corridors may be omitted. 

Certain other points should be noted in regard to this framing 
plan, as follows: 

Columns should not he put at the front of elevators, as they cannot he 
fireproofed without interfering with the clear space of shaft. 

Beams, if possible, should always be framed at right angles to girders, 
as oblique connections are expensive. 




58 


STEEL CONSTRUCTION 


Beams should not frame off center of column if a little change in either 
column or beam can obviate it. 

Columns on adjacent and parallel lines should, as far as possible, be 
opposite each other; that is, a beam framed to the center of one column 
should also meet the center of the next line of columns. 

Spacing and spans of beams should be such as to develop their full 
strength. 

Fig. 45 shows the wall sections and the resulting spandrel 
sections and wall girders. Not all the points that arise in such a 
framing can here be brought out; but from the foregoingthe gen 
eral method of treatment of such problems should be clear. 

In buildings of a different character, many different and often 
more complex conditions will arise. The student, however, must 
always bear in mind that it is the duty of the designer to grasp 
fully the architect’s details, and so to arrange his framing as to 
conform in all respects thereto, unless such details can themselves 
be changed more readily and to better advantage. It is essential 
for the designer to see not only what has already been determined, 
but what details will result when certain features are fully worked 
out; and in all his work the economy of design and framing, and 
the efficiency of the framework, should be kept constantly in mind. 

The framing shown for this building is more especially 
designed for concrete floor arches. In cases where terra cotta 
arches are used, a somewhat different arrangement of columns 
would probably be made. 

In the framing of floors and roofs, it is not always advisable 
to use the exact sizes and weights of beams that are theoretically 
required; there are often a number of practical considerations 
affecting the determination. As previously stated, standard sizes 
and weights should be used wherever, practicable, as ordinarily 
these sizes are much more readily obtainable than others. If the 
general framing consists of standard sizes, and a few beams are so 
loaded as to require special sizes and weights, some change should 
if possible be made to avoid this, as to insist on the furnishing of 
a few beams of odd weights might cause serious delay in the 
delivery. In certain cases where it is of special advantage to make 
nearly all the beams of special weights, arrangements might be 
made for the delivery, provided the tonnage is large. 

Beams, as far as possible, should be of the same size through- 



STEEL CONSTRUCTION 


bd 





Fig. 46. 

















































































































































60 


STEEL CONSTRUCTION 


out a given floor, since for a level ceiling different depths of beam 
would require furring, or extra filling, or special arches. Where 
girders of short span carry the ends of heavy beams or girders, it 
is sometimes necessary to use an uneconomical section in order to 
get a sufficient connection. For instance, a 10-inch beam might 
be strong enough to carry a 15-inch beam; but the connection 
could not be made to a 10-inch beam, and therefore a larger sized 
beam or channel should be used. In general the girder should be 
of the same depth as the beam, or nearly so, unless the beam rests 
on top of the girder or is hung below it. 

In some cases also — generally where small beams are used — 
the standard end connections are not sufficient, and it may be 
necessary to use larger sizes. 

Other special conditions of framing are likely to arise, affect¬ 
ing the determination of sizes, so that the designer, in laying out 
the framing, should keep in mind the feasibility of making proper 
connections for framing the different parts. 

When very heavy loads are carried by beams of short span, it 
is necessary to use a section that will have sufficient web area to 
prevent buckling.* In such cases, the sizes of beams may be deter¬ 
mined by this condition rather than by the bending moment caused 
by the loads. The tendency to cripple is greatest at the ends, and 
in order to determine the allowable fiber strain, a modification of 
the column formula as given below is applicable. The total shear 
should be considered to be carried by the web, and the combination of 
horizontal and vertical shear is equivalent to tension and compres¬ 
sion forces acting at an angle of 45° with the axis of beam. The 
unsupported length in the formula, therefore, is the length between 
fillets on a line making 45° with the axis of beam. 

Tie Rods. Tie rods should be spaced at distances not greater 
than twenty times the width of flange of floor beams. 

The size of tie rods is generally | inch diameter. An approxi¬ 
mate determination of the required size can be made by use of the 
following formula giving the thrust from floor arches: 

T _ 3WL 2 

2 R ’ 

where T = thrust in pounds per linear foot of arch, 




STEEL CONSTRUCTION 


61 


W = load per square foot on arch, 

L = span of arch in feet, 

R = rise (in inches) of segmental arch, or effective depth of 
flat arch.* 

The spacing of the tie rods being known, the total strain on 
the rods is the thrust, as above, multiplied by the spacing. Divid¬ 
ing this by the safe fiber strain of 15,000 lbs. per square inch, 
gives the net area of rods, or the area at the root of threads, and 
thus determines the diameter of the required rod. 

The spacing of tie rods is generally determined by providing 
one or more lines dividing into equal spacing the length of beams 
between connections or walls. The number of lines is determined 
by the necessity of keeping the thrust within the capacity of a cer¬ 
tain size rod, or by the limit of twenty times the flange width. 

FIREPROOF AND FIRE-RESISTING 
MATERIALS. 

The functions of fire-resisting materials are threefold: 

1. To carry loads. 

2. To protect all structural steel. 

3. To serve as noncombustible partitions or barriers. 

The specific uses are, in general, the following: 

1. Floor and Roof Arches. 

2. Ceilings. 

3. Partitions. 

4. Protection for flanges and webs of beams and girders. 

5. Protection of columns, doors, and shutters. 

Fireproof materials, as generally used at the present time, 
comprise burnt clay in various forms, concrete, and plaster. 

Fire-resisting materials, in general, comprise specially treated 
wood, certain kinds of paint, asbestos paper or other special kinds 
of paper, and metal-covered wood. 

* Note" By “ effective depth of flat arch” is meant the depth from 
top of arch to bottom of beam. 




G2 


STEEL CONSTRUCTION 


Plate E 


f7y-46. 

Chat Construct/or Term Cotta Arch. 


r/ 9 -47 

S/de Construcf/on % Term Cotta Arch 


rt f - 43 

Ce/t/ny and Roof* 77k B/ock Constructto/7. 



Seymentat Terra Cotta Arc/7 Construction^ 


~W/~ '"-y 


r/f-5o 
Brick Arch Construet/orr. 


ttys/ 
Corrugated Iron Arch 
Construe t/o/7 


FLOOR AND ROOF ARCHES. 

Terra Cotta Floor and Roof Arches. Burnt-clay products 
include brick, porous tile, and hard or dense tile. The latter two 
are commonly called terra cotta. 



























STEEL CONSTRUCTION 


63 


The use of brick for arches between beams has, in building 
construction at least, become almost entirely obsolete. This is due 
largely to the saving in weight accomplished by the use of other 
materials. 

When brick arches are used, the construction is generally of 
the type shown by Plate II, Fig. 50. There is a patented system 
employing brick, which is known as the Rapp system. The bricks 
here do not form a self-supporting arch, but are laid flat between 
metal ribs or bars that spring between the steel beams. 

The use of burnt clay products in fireproof floor and roof 
arches and coverings of steel, is confined almost exclusively to 
terra cotta, and this is generally of the porous type. 

Porous terra cotta is lighter and less brittle than the hard 
tile, with probably almost equal strength. It is made by mixing 
straw with the clay, the mass, when burned, being thus left por¬ 
ous. It also has the advantage that it can be nailed into, this 
being especially important in roof and partition blocks. 

Terra cotta arches were formerly laid up exclusively with the 
ribs running parallel to the beams, this construction being known 
as side construction. Tests have shown, however, that the arch 
is stronger when laid with the ribs at right angles to the beams; 
and this practice, which is known as end construction, is now 
generally followed. Figs. 46 and 47 (Plate II) show these two 
constructions. 

An inspection of these cuts will show that the arch consists 
of a key, voussoirs, and • skew-back, shaped similarly to the prac¬ 
tice in masonry arches. It should be noticed that in side construc¬ 
tion a special-shaped skew-back is required, which is not the case 
in end construction. Also notice that the piece protecting the 
flange of the beam is separate from the arch, this being a simpler 
plan than to shape the skew-back so as to cover the flange. 

The arch is generally two inches lower than the bottom of 
the beam, thus coming flush with the flange piece and giving a 
flush surface for plastering. 

The construction of wood screeds and top flooring shown is 
almost always used, although other forms could be adopted. The 
filling between the screeds should always be a cement concrete, 
although cinders instead of stone may be used. 





64 


STEEL CONSTRUCTION 


The method of supporting the centers for these arches is 
shown by Fig. 52. This construction allows the centers to be 
readily removed after the arch has set. 




CENTERS FOR TERRA COTTA FLOOR ARCH. 

%• 52 . 

The practice, in general, is to set the floor arches, from 
the lower floors up, after the steel frame has been carried several 
stories in advance. Centers used in the lower floors can be used 
in the upper floors unless the work progresses very rapidly. 

Roof arches, on account of the pitch of the beams, have to be 
furred down to give a level ceiling. Terra cotta blocks may be 
used for this purpose, as shown in Fig. 48. It is, however, quite 































































STEEL CONSTRUCTION 


65 


as common, even where terra cotta floor artd roof arches are used, 
to form the furred-down ceilings of small channels or angles 
covered with some form of wire lath. A construction of this sort 
is shown in Fig. 53. 

For ordinary loads it is not usually necessary to calculate the 



Fty 53 


depth of terra cotta arch required. The spans are kept within 
certain limits, and for such limits the proper depth of arch has 
been well determined. 

The following spans and depths of arches represent the 
accepted practice: 
































































66 


STEEL CONSTRUCTION 


When it is desired to use terra cotta construction for heavy loads, such 
as in stores and warehouses, a segmental arch is used, generally 4 inches or 
C inches in thickness. The filling above the arch consists of concrete, either 
of stone or cinders. This construction is illustrated in Fig. 49. While 
greater spans are sometimes used, the best practice does not exceed about 
8 feet, and is preferably limited to 6 feet. 

Guastavino Arch. This is a dome or vault system especially 
adapted for long spans where a flat ceiling effect is not essential, 
as in churches, libraries, halls, etc. 

The construction consists of several layers of hard tile one 
inch thick, laid breaking joints. The number of layers varies with 
the conditions, but generally does not exceed four. The rise of 
the dome is ordinarily not great; and it rests either between walls 
or, in some cases, on heavy girders. The tiles are usually set 
in Portland cement, except that the first course is set in plaster in 
oraer to obtain a quick set and to dispense with a certain amount 
of centering. 

This system is almost always installed under a guarantee from 
the company controlling the patents, as to its efficiency and adap¬ 
tability to the conditions of the special case in hand. 

' Concrete-Steel Floor and Roof Arches. The types of concrete 
and concrete-steel arches are becoming more numerous each day, 
and only a few will here be discussed. They may be separated 
primarily into flat arches and segmental arches. In most of the 
systems of the flat-arch construction, the action is essentially that 
of a beam of concrete in which metal is embedded on the low side 
to increase the tensile strength, since concrete is not as strong 
in tension as in compression. In a few of the systems, however, 
when special-shaped bars are used at short intervals, the effect 
is more that of a simple slab of concrete supported by these bars, 
which act as small beams between the main floor beams. 

In the segmental form of concrete construction, the metal, 
where used, is generally intended more as a permanent center for 
forming the arch and for supporting it until the concrete has fully 
set, when the concrete is considered as taking the load independ¬ 
ently of the steel center. 

Plate III shows types of Expanded Metal Floor Construction. 
Fig. 54 shows System No. 9, which can be adapted to, long spans. 
It is not the general type of this form of construction, however, as 



STEEL CONSTRUCTION 


G7 


the types shown below are generally considered more economical. In 
calculating the weight of the construction, the arch should be figured 


For Systems Nos. 3 and 5. 

A.B.C.E H. same as for No. 9. 

I) i= slab of cinder concrete. 

K = angles for support of ceiling. 

L = expanded metal ceiling. 

M= hangers securing ceiling angles to 
beams. 

N = slab of cinder concrete on expanded 
metal, protecting webs of oeams, 

O = solid concrete haunch protecting 
web of beams. 

For System No 7. 

A.B.C.D.E. same as for No. 9. 

O = solid concrete slab. 


For System No. 9. 

A = top floor. 

B = under floor. 

C = wood screeds or sleepers. 

D = arch, cinder concrete. 

E == expanded metal sheet. 

F = cinder concrete filling around and 
under screeds. 

G = expanded mStal wrapping of flanges 
to receive screened plaster as shown 
at P. 

H= main floor beam. 

J = tie rods. 

For System No. 8. 

A.B.C D.E.F G.H. same as for No. 9. 

For System No. 4. 

A.B.C D E.H. same as for No. 9. 




separately from the filling above, as the weights of these are different. 
The same remark applies to all systems of concrete construction. 















































































68 


STEEL CONSTRUCTION 


Fig. 55 shows System No. 3, with a furred-down ceiling to 
give a level effect. This ceiling is not a necessary part of the 
construction, and is often omitted. The space between ceiling and 
floor slab is available for running of pipes, wires, etc.; and, to avoid 
punching of beams when such use is made of this space, the ceiling 
is dropped below the flanges of beams far enough to allow the 
passage of pipes, wires, etc. 

This system is the one generally employed for long spans and 
heavy loads, as it gives the most substantial protection to the steel, 
and has certain elements of strength not possessed by the other 
systems, as follows: The haunches, besides protecting the webs 
and flanges of beams, shorten in effect the span of floor slab, and 
stiffen the floor beams against side deflection. The sheets of 
expanded metal can be made in effect continuous over all floor 
beams, and, because of this, the whole construction from wall to 
wall acts together, and has the advantage of a continuous beam 
over a number of supports. While it is impossible to state exactly 
what this advantage amounts to, on account of the uncertainty 
of actual conditions conforming to the theoretical assumption, 
it is probably safe to assume that the strains in the floor slab of a 
construction having this continuous feature would not be more 
than three-quarters as much as if the slabs were discontinuous. 
It should be noted in the above system, that if the furred ceiling 
is omitted the lower flanges of the beams are protected in a man¬ 
ner similar to that shown for System No. 7. 

System No. 5, illustrated by Fig. 56, differs from System 
No. 3 only in the method of protecting the beam. As will be seen, 
all the strength afforded by the haunch is lost by this construction, 
and, as will also be seen later from results of tests, the protection 
is much less fireproof. 

Fig. 57 shows System No. 4, which differs from System No. 3 
only in the entire omission of protection to floor beams. This 
system is therefore only semi-fireproof, and in event of fire in the 
story below would not be to any degree fireproof. It is sometimes 
used with a fireproof suspended ceiling, but, as will be noted 
further on, tests of such ceilings have shown them to be of ques¬ 
tionable value as efficient fire barriers. 

Fig. 58 shows System No. 8. This system is chiefly adapted 




STEEL CONSTRUCTION 


69 


to light loads on moderately long spans where the beams are in 
general not over 8 inches or 9 inches deep. In such cases, where 
a flush ceiling is desired, it is sometimes more economical than 
some of the other systems with suspended ceiling. 

It has the disadvantage from the standpoint of strength, that 
the load all comes on the lower flanges of beams, and further, that 
all continuous effect of slabs is lost. 

Fig. 59 shows System No 7, really a modification of System 
No. 3, in which, in order to save depth, the floor slab is flush with 
the top of the floor beams. 

This system also has the disadvantage of loss of continuous 
effect. In all the above systems, the more common spans are 
from 5 feet to 8 feet. The company controlling the patents, how¬ 
ever, claim to be able with safety to adapt the construction to 
longer spans, even under heavy loads. 

In these systems, as well as in all others where a cinder filling 
is used on top of the floor slab, the filling should contain some 
cement, as otherwise the unneutralized cinders are likely to cause 
corrosion of the steel. 

The depth of floor slab varies with the load and the span, but 
is ordinarily 3 inches or 4 inches for loads under 200 lbs. and 
spans of about 5 feet. 

Plate IV illustrates types of the Roebling system of fireproof 
floors. Fig. 60 shows System A, Type 1, which consists in general 
of a wire center sprung between the bottom flanges of floor beams, 
and upon which is deposited cinder concrete in the form of a seg¬ 
mental arch whose top is flush with the top of floor beams. 

The strength of this system is considered to be simply that of 
the concrete arch, the wire center being intended merely for the 
support of the concrete until it has set, and for a permanent center 
upon which plastering may be applied directly if a level ceiling is 
not desired. This construction, Type 2, is shown in Fig. 61. It 
is further claimed for this wire centering, that it facilitates the 
more rapid drying out of the concrete on account of exposing both 
surfaces to the air and allowing the surplus water to drip through. 

Fig. 62 shows System B, Type 1. This is a flat arch con¬ 
struction in which the steel members are bars spaced generally 
about sixteen inches center to center, the concrete slab being 



70 


STEEL CONSTRUCTION 


usually 3} inches thick. The bars are tied transversely by wire 


rods spaced about 24 inches on 
bars in place. 

Plate IV Types 

For System B. 

A.B.C.H.R.S.K.L same as for Sys. A. 

D = cinder concrete floor slab. 

M = flat bar 2 " x fa" or 2" x 
N = solid casing of cinder concrete. 

O = l" x fa" flat bar. 


Note:—Items R.K.O apply to Typel only. 

Item L applies to Types 1 and 4 only. 


centers and serving to keep the 


of Roebling System of Floor Construction 

For System A. 

A = top floor. 

B = under floor. 

C — wood screeds or sleepers. 

D = cinder concrete arch. 

E = steel rod {fa" or fa") woven into wire 
lathing. 

J = tie rods. 

H= main floor beams. 

S = plaster ceiling. 

R= supporting wire. 

K= clamp supporting ceiling. 

L = steel rods woven into wire lathing. 
Note: — Items R.K.L apply to Type 1 only. 



System A - Trpc-J 
rigr 60 



.N\ 



System-3 - Trpe-4 
F/g. * 64 

Fig. 63, Type 2, shows the construction when the suspended 
ceiling is omitted. This suspended ceiling does not always have 
the bars shown by Fig. 62, but for short spans has simply the wire 
cloth stiffened by rods woven into it. 





























































































STEEL CONSTRUCTION 


71 


Fig. 64 shows System B, Type 4, in which the floor slab rests 
on the lower flanges, and the cinder filling is flush with the top of 
floor beams. This system makes some saving in depth, but is 
open to certain objections, one being the disadvantage from the 
standpoint of strength of resting the slabs on the bottom flanges, 
and another the absence of all protection or covering for the top 
flanges of beams. 

The practice of the company controlling the patents is to 
deposit the concrete without any tamping such as is ordinarily 
done in the other systems. The claim is made that this method 
insures lightness and preserves its porosity, being thus rendered 
less subject to the effects of changes of temperature, either of the 
outer air or under exposure to fire and water. 

As will be noted later, Professor Norton advocates tamping of 
concrete to eliminate the possibility of voids, which he shows to 
be always productive of corrosion of the steel. 

Plate V shows types of the Columbian system of fireproof 
floors. This is a flat arch system, in which the action of the floor 
slab is that of a concrete beam with imbedded steel bars. 

No continuous effect such as is had in some of the other 
systems exists in this construction, except as the whole construction 
of girders and their casing may be considered as acting together. 
The connection of the bars to the floor beams, and the concrete 
being finished flush with tops of beams, make the slab, considered 
by itself, discontinuous. 

In the systems previously described, cinder concrete is almost 
invariably employed. In this system, however, the use of stone 
concrete is the prevailing practice. 

The different types vary only in the size and spacing of the 
imbedded bars (and consequently in the thickness of the concrete 
slab) and in the connection of these bars to the beams. This con¬ 
nection is made either by means of small angles bolted to the webs 
of floor beams similarly to regular beam framing, or by means of 
hangers resting on the top flanges of beams. The former construc¬ 
tion is used only when special stiffness of the frame is required, as 
in high building construction. 

The thickness of slab is generally 1-j inches more than depth 
of bar. The spacing of bars and of beams varies with the required 



72 


STEEL CONSTRUCTION 


loads. The different cuts shown (Figs. 65, 66, and 67) give 
reasonable limits. In any case of special loading, however, or of 
spans exceeding 8 feet, tests should be made in accordance with 
the required conditions. 

The explanations given on the plate, in connection with the 
above, should make the construction clear. It is the practice, in 
using this system, to have slots in the brick walls at the level of 
the floor slabs, and the bars and concrete slabs - are then imbedded 
in these slots. This gives a good tie for the walls, and obviates 
the necessity of channels against the walls to take the floor con¬ 
struction. 

In all calculations of the weight of dead loads where this 
system is used, the difference in weight between cinder concrete 
and stone concrete must be noted. 

Figs. 69 and 70 show the Ransome system of floor construc¬ 
tion. This is one of the oldest forms of concrete-steel construc¬ 
tion, and is used in various modified forms to suit different 
conditions. It consists of steel rods imbedded in the tension side 
of the concrete; these rods run transversely to the beams, and are 
tied longitudinally by other rods. In some forms of this construc¬ 
tion, steel girders and beams are replaced by deep concrete beams 
with heavy rods imbedded therein, and tied at intervals by 
U-shaped rods. The use of rods in the concrete makes possible 
many varied forms of construction, but special knowledge of the 
subject is required to design such forms properly. 

The use of concrete and concrete-steel arches cannot as yet 
be considered to be very general. They are of comparatively 
recent introduction; and although, in the aggregate, they may 
now be said to be extensively used, there is as yet no one form 
recognized as standard. 

The Building Departments of all cities have required special 
and severe tests of full-sized arches to be made before allowing 
any of the types to be used in construction. Their use is un¬ 
doubtedly growing, and perhaps more especially in warehouses 
and buildings of heavy construction. There are certain features 
not possessed by any of the concrete systems; and this fact,,prob¬ 
ably, to a great degree explains the more general use of terra cotta 
in office buildings. 



STEEL CONSTRUCTION 


73 


Plate V' 


^ • 

Types °f Columbian System of Fireproof F/oors 


Aor System] //q§ 

r* r/bbed bars imbedded 
in Concrete f£ omept ') 

xT' Stirrups. 
forSystem ffo <5- 

G - concrete ce/t/ny slab 
M‘ / 'r/bbed bar /nbedc/ect 
/r corecrete 

/Vote , Stems rot m entiore d 
above ore same as for- 
•Systrer t fta /. 


for System /Vj./ 

A • top ytoor. 

Eb m under f/oor. 

C/ m u/ood screeds ors/eepers 
£O m Cinder concrete ft///no 

Concrete poor s/ab/tb/cAness-/it depth of bar) 

t ribbed bororb! )embedded in Concrete 
Gr’ castntf of f/oot beams. 

H’ S/obprotecting f/anyes of ftoor beams, 
xf- any/es connectmy bars to f/oor beams 
r.’ main f/oor beams 
t— ' c once a led anchors ho/diny stab 






Connection of Col/nrbian 
f/oors/ab to bncA wa/ts 
fiy 63. 
























































































































74 


STEEL CONSTRUCTION 


As noted previously, an important feature in buildings not 
having heavy masonry walls is lateral stiffness. This lateral stiff¬ 
ness is secured to a considerable degree by the floor construction, 
which serves to tie together all parts of the framing at each floor 
level, and also to distribute the lateral strain throughout the 
whole. 

A floor construction which fills the whole depth of the beams 
is therefore better calculated to perform this function than one 
that is comparatively thin, as are nearly all the concrete systems. 
Another important consideration concerns uniformity of material. 
Porous terra cotta, like brick, is easily inspected, and a nearly 
uniform product can thus be secured. The strength of concrete 
and of concrete steel, however, depends very largely upon the use 
of proper materials and their proper mixing and laying in place. 
Much greater variation is here likely to occur, and consequently a 
greater or less uncertainty as regards uniformity of results must 
exist. Another point to be considered is the necessity of having 
the concrete or concrete-steel system installed by the company 
controlling it, this resulting from the patents covering each form 
of construction. A still further advantage is the flush ceiling 
given by the terra cotta blocks. 

There are, however, numerous points to be cited in favor of 
many of these systems. The general trend of investigation and 
discussion is toward a better understanding of the possibilities of 
concrete steel in general, and this will not unlikely result in the 
future in its more extensive use. 

It is not the general practice of individual designers to calcu¬ 
late the required depth of slab in the above systems, except in 
the case of unusual loads and spans; but, as in the case of the 
terra cotta systems, tests have largely determined the limits of 
spans for various depths and loads. As concrete arches are used 
for heavy as well as light loads, however, there is need of more 
exact data than is at present available to determine their capacities 
under different conditions. 

It cannot be said to be conservative practice in any of these 
systems, much to exceed eight feet in the span of the arches. 
The uncertainty of the quality of the concrete when cinders are 
used, and the uncertainty of set in the deeper slabs, together with 






STEEL CONSTRUCTION 


75 


numerous other circumstances likely to affect the uniformity of 
the product, make it important to keep within this limit. 

As will be seen from the illustrations, nearly all the concrete 
systems require furring down to give level ceiling. 

Tests of Floor and Roof Arches. The most severe test of 
all forms of floor arch is their exposure to fire and water when 
underload. As above stated, one of the functions — and a very 
important one — of all fireproof materials is to protect the steel; 
for, if the covering falls off, leaving the steel members exposed to 
fire, the steel frame will soon fail. None of the materials used — 
terracotta or concrete in its various forms — are of themselves 

Types of Ransome Floor Construction 


4~ Gars /(L C/oC 



Fig 69 



Fig 70. 

combustible. Failure, when it occurs, is generally due to expan¬ 
sion and contraction caused respectively by the intense heat and 
by the chilling effect of the stream of water, and to the force of 
the stream knocking off pieces that become loosened. All of the 
systems in general use have been subjected to very severe tests of 
this character without collapse, before being accepted by the differ¬ 
ent Building Departments; and it is probable that when failure 
occurs in actual building fires it is due to constructive defects, 
there having been less careful construction than was used in the 
tests. 























76 


STEEL CONSTRUCTION 


If only a small portion of the covering becomes detached, the 
whole adjacent construction is seriously endangered. It will be 
seen from the above that failure is more likely to start from de¬ 
tachment of the covering of beams, girders and columns, than in 
the body of the arch, and such covering should be as substantial 
as possible. For this reason, haunches or a solid filling protecting 
the beams and girders are preferable to wire lath wrapping the 
same. 

Tests by the New York City Building Department on floors 
having suspended ceilings of wire lath and plaster, resulted in 
these ceilings being entirely destroyed. Tests of different floor 
systems having rolled shapes, such as T bars or special-shaped 
bars, imbedded in the concrete slabs, showed less deflection under 
loading than when a mesh of wire rods was used. 

The method of testing floor arches is as follows: A brick 
furnace is built, having a large combustion chamber, the top being 
of the floor construction to be tested. This arch is loaded with a 
load generally four times that specified. Measurements of deflec¬ 
tions due to the stress are taken before and after exposure to the 
fire. During this exposure, which generally lasts several hours, a 
temperature of from 2,000° to 2,500° is constantly maintained. 
After some time a stream of water from a fire nozzle is played on 
the arch, thus reproducing as nearly as practicable actual condi¬ 
tions. 

After the test, the load is removed to see how great the per¬ 
manent deflection is. It is important in all loading tests to have 
the load applied over a definite area, so that the exact load per 
square foot can be determined, and to avoid all possibility of any 
portion of the load bearing on the beams instead of on the arch. 

The results of some tests made under different conditions are 
here given: 

A fire and water test on a concrete expanded metal floor 
composed of 6i inches of concrete mixed in the proportion of 1 
part Portland cement, 2 parts sand, and 5 parts cinders, showed 
the following results: 

The slab was of a type similar to that shown in Fig. 55, the 
beams being 20-inch beams and spaced about 12 feet center to 
center, with the span of the beams about 17 feet 9 inches. 



STEEL CONSTRUCTION 


77 


The slab of concrete was loaded with 400 lbs. per square foot, 
under which it deflected .30 inch. Under exposure to fire the 
deflection increased to 2|- inches, and when the test was completed 
remained about 3| inches. 

A portion of the under side of the concrete was knocked off 
by the stream of water. 

A test under practically the same conditions as above was 
made of the Columbian system. The type was of the general form 
shown by Figs. 65 to 67. The spans were the same as above. The 
slab was 8^ inches in depth, composed of 1 part Portland cement, 
2^- parts sand, and 5 parts broken stone. The bars were 5-inch 
bars, spaced 2 feet center to center, and fastened to the beams by 
angles. 

A portion of the girder covering consisted of mackite blocks 
plastered, another portion consisting of 2-inch cinder concrete, the 
latter being the regular construction. There were also two 8-inch 
I-beams set up, one covered with cinder concrete to 9 inches X 
13 inches; the other covered with hollow bricks to 12 inches X 
16 inches, giving 4 inches covering. 

The floor was first loaded with 1,000 lbs. per square foot, 
under which it deflected | inch. The load was then reduced to 
400 lbs. per square foot, and the fire test commenced. This lasted 
for two and one-quarter hours at a maximum temperature of 1,700°. 
A stream of water was then applied for 4J minutes, and afterwards 
another fire test given of 38 minutes and a second stream of water 
applied. The floor, at the end of the test, showed a deflection of 
1| inches. The cinder concrete beam and column coverings were 
not materially damaged. The mackite covering was entirely 
stripped off, and the hollow brick column covering badly damaged. 
No apparent injury occurred in the floor slab. After this test the 
floor was loaded up to 1,650 lbs. per square foot, at which point 
the walls of the test house made it necessary to stop. The net 
deflection under this load was 1| inches. A few cracks appeared 
in the ceiling under this load, most of them being parallel to the 
bars.* 

Numerous other tests of expanded metal floors on shorter 

*Note. A detailed report of these tests is given in Engineering News, 
June 27, and November 21, 1901. 





78 


STEEL CONSTRUCTION 


spans have shown satisfactory results. For spans up to 8 feet and 
loads under 200 lbs. per square foot, which are the ordinary condi¬ 
tions, the cinder concrete shows safe results. Beyond these limits 
special tests should be made in each case. 

A valuable review of the effects of a practical fire test on 
terra cotta and concrete floor construction, is given in the discussion 
bearing on the fire that occurred in the Horne Building, Pittsburg, 
Penn., May 8, 1897, which was published in Engineering News , 
May 20 and 27, and July 1 and 15, in that year. An account 
of a second fire which occurred on April 7, 1900, is published 
in the same periodical under dates of April 12 and April 26, 
1900. 

The New York Building Department conducted a test on 
three arches of the Guastavino type, each 3 feet in length. The 
spans were 6 feet, 10 feet, and 12 feet. The 6-foot span was 
composed of 2 courses of tile, making a thickness of 21 inches; 
the 10-foot span, of four courses, giving 5 inches thickness; and 
the 12-foot span, of three courses, with a total thickness of 3J 
inches. All were leveled up with concrete. The 6-foot span 
carried 2,500 lbs. per square foot, and showed a maximum deflec¬ 
tion of .13 inch. The 10-foot span carried 3,600 lbs. per square 
foot, with a deflection of .19 inch. The 12-foot span carried 3,125 
lbs. per square foot, with a maximum deflection of .32 inch. 

This was a simple loading test with do application of fire and 
water. 

Tests of porous terra cotta hollow tile arches have not been 
so numerous, especially under fire exposure. Table XIII gives 
the results of a series of tests to determine breaking loads of differ¬ 
ent arches, and is taken from the “ Transactions ” of the American 
Society of Civil Engineers, Nos. XXXIY and XXXV, of 1895 
and 1896. 

In terra cotta arches as in concrete arches, great variations in 
strength will result from varying degrees of thoroughness in con¬ 
struction. These arches should always be set in cement and care¬ 
fully keyed, and the use of broken blocks should be avoided. 
Settlement in arches of this type often results in cracks in tile or 
mosaic floors. 




STEEL CONSTRUCTION 


79 


TABLE XIII. 


Breaking Loads of Hollow Tile Arches. 


Depth 

of 

Arch. 

Rise. 

Span. 

Length. 

Total 

Load. 

Load 

per 

Sq.Foot 

Total 

Hori¬ 

zontal 

Thrust 

Hori¬ 
zontal 
Thrust 
per Ft. 
of 

BLOCKS. 

Character 

of 

Load. 

Manner 

of 

laying 

Joints. 

CO 

I 

aS 

Ins. 

Ins. 

Ins. 

Ins, 

Lbs. 

Lbs. 

Lbs. 

Arch. 

6. 

8.5 

60 

48. 

13750 

688 

29474 

7369 

E 

Hard 

Dis. 

Port 

7.5 

5. 

46 

11.5 

9000 

2452 

10367 

10818 

u 


« 

N. M. 

7.5 

5. 

60 

35.2 

11250 


33750 

11505 

(( 

u 

Cen. 

Port 

7.5 

5. 

60 

36.5 

13000 


39000 

12822 

u 

Porous 

u 

u 

8. 

7. 

60 

38.25 

14500 


31071 

9747 

u 

u 

u 

(C 

8. 

7. 

60 

38.25 

15750 


33750 

10588 

u 

Hard 

u 

<( 

12. 

10. 

60 

41. 

16400 


24600 

7200 

u 

u 

a 

a 

12. 

8.75 

60 

10. 

3100 


5314 

6377 

U 

<( 

u 

N. Me 

12. 

9. 

60 

10. 

5000 


8333 

10000 

a 

« 

(t 

<t 

12. 

9. 

60 

10. 

15100 

3630 

12583 

15100 

<( 

u 

Dis. 

t< 

12. 

9.5 

60 

10. 

2500 


3947 

4736 

u 

u 

Cen. 


8. 

5.5 

46 

11.5 

2500 

681 

2614 

2727 

s 

u 

Dis. 

N. M. 

8. 

5. 

45 

11.5 

1300 

362 

1463 

1526 

({ 

u 

u 

<t 

8. 

6. 

60 

36. 

10000 


25000 

8333 

« 

« 

Cen. 

Port 

8. 

5. 

60 

36. 

5700 

380 

8550 

2850 

1C 

u 

Dis. 

u 

8. 

5. 

60 

12. 

3500 

700 

5250 

5250 

(( 

« 

<( 

N. M. 

8. 

5.5 

60 

12. 

10000 

2000 

13636 

13636 

u 

u 

u 

a 

* 8. 

5.5 

60 

12. 

2500 


6818 

6818 

o 

u 

Cen. 

it 

8. 

5.5 

60 

24. 

9950 

995 

13568 

6784 

a 

u 

Dis. 


8. 

5.5 

60 

24. 

2500 


6818 

3209 

u 

<( 

Cen. 

<< 

10. 

7.5 

60 

36. 

13500 

900 

13500 

4500 

(t 

u 

Dis. 

Port. 

10. 

8. 

60 

37. 1 

14500 

940 

13594 

4408 

u 

. . . . - 

U 

u 



In the above table the following abbreviations are used: “E” — end 
construction; “fe”— side construction; “H”— hard clay: “Porous” — 
porous terra cotta; “Dis.” — distributed load; “Cen.”—concentrated loa ' 1 
at center; “Port.” — Portland cement; “ N. M.” — no mortar. 

The loads per square foot in the above table were obtained by dividin, 
the total load by the superficial area of the arch in square feet. The liori 
zontal thrusts were obtained by the regular formulae; for central loads thes* 
are double the thrusts for distributed loads of the same weight. 


SELECTION OF SYSTEfl. 

Not any single system, probably, wo aid be used in all cases 
even if tlie designer were to choose without any conditions affect¬ 
ing his selection. Some systems are naturally better adapted than 
others to certain conditions. Practically there are always a num¬ 
ber of considerations affecting the choice. No attempt will be 
made here to specify to what conditions certain systems are better 
adapted than others, as this is largely a matter of judgment at the 
present time. The considerations in general, however, are as 
follows: 

Light or heavy live loads ; dead weight of construction, and con- 































































80 


STEEL CONSTRUCTION 




sequent spacing of beams and span of arches ; necessity of lateral 
stiffness in door system; possibility of using paneled ceiling, and 
consequent increase of clear height story between beams ; necessity 
of flush ceiling, and comparative advantage of solid floor system 
and furred-clown ceiling; protection afforded webs and flanges of 
ba.ims and girders by different systems; possibility of omitting tie 
rods and a certain amount of steel in some systems; corrosive 
effects on steel under certain conditions ; rapidity of construction, 
and allowance for final setting of concrete under certain conditions 
of weather and of heavy loadings; and comparative cost of differ¬ 
ent systems. 

The weights of hollow-tile floor arches and fireproof materials, in 
pounds per square foot, are given in the following table: 

table xiv. 

Weights of Hollow-Tile Floor Arches and Fireproof riaterials. 


END CONSTRUCTION, FLAT ARCH. 


Width of Span Between Beams. 

Depth of Arch. 

Weight per Square Foot. 


5 feet to 6 feet. 

8 inches. 

27 pounds. 


6 

“ 7 

it 

9 « 

29 

it 


7 

“ 8 

ii 

10 “ 

33 

ii 


8 

“ 9 

n 

12 “ 

38 

<i 



HOLLOW. RRICK FOR FLAT ARCHES. 


Width of Span Between Beams. 

Depth of Arch. 

Weight per Square Foot. 

3 feet 6 inches to 4 feet 0 inches. 

6 inches. 

27 pounds. 

4 “ 0 

<i 

4 

ii 0 n 

7 “ 

29 

ii 

4 “ 6 

u 

5 

“ 0 “ 

8 “ 

32 

ii 

5 « 6 

u 

6 

ii o n 

9 “ 

36 

n 

6 “ 0 

(( 

6 

“ 6 « 

10 “ 

39 

ii 

6 “ 6 

u 

7 

n o a 

12 “ 

44 . 

it 




PARTITIONS. 




Thickness. 

Weight per Square Foot. 

Hollow Brick (Clay) Partitions 

2 inches. 

11 pounds. 

u 

M 

n 

II 

3 « 

14 

it 

u 

(1 

it 

II 

4 “ 

15 

ii 

a 

It 

ii 

II 

6 “ 

19 

it 

(i 

II 

it 

li 

6 “ 

20 

it 

« 

II 

n 

II 

8 “ 

27 

n 

Porous Terra-Cotta Partitions 

3 “ 

16 

a 


II 

ii 

II 

4 “ 

19 

ii 

<t 

II 

n 

II 

6 “ 

22 

u 

<1 

II 

a 

II 

6 “ 

23 

ii 

u 

II 

ii 

li 

8 « 

33 

ii 
































STEEL CONSTRUCTION 


81 


pautitions — (Concluded). 







Thickness. 

Weight per Square Foot. 


Porous Terra-Cotta Furring 

2 inches. 

8 pounds. 


u 

it 

it 

Roofing 

2 « 

12 “ 

• 

u 

it 

ii 

ii 

3 “ 

15 « 


it 

it 

it 

it 

4 “ 

19 “ 


it 

it 

ii 

Ceiling 

2 “ 

11 “ 


it 

it 

it 

ii 

3 « 

15 “ 


it 

it 

it 

ii 

4 “ 

19 “ 


6 inch Segmental Arches, 27 pounds per square foot. 

g_ a « <( 33 it u u u 

2 inch Porous Terra-Cotta Partition, 8 pounds per square foot 
The following table shows the safe loads in pounds per square 
foot uniformly distributed for liollow-tile floor arches. 


TABLE XV. 


Safe Loads Uniformly Distributed for Hollow=Tile Arches. 


Nominal 

Depth. 

Effective 

Depth, 

R 

Span of Arch in Feet = L. 

Inches. 

Inches. 

3 

4 

5 

6 

7 

8 

6 

3.6 

336 

189 

121 




7 

4.6 

429 

242 

155 




8 

5.6 

623 

294 

188 

131 



9 

6.6 

616 

347 

222 

154 

113 


10 

7.6 

709 

399 

255 

177 

130 

100 

12 

9.6 

896 

504 

323 

224 

165 

126 


Gross loads in pounds per square foot, i. e ., including weight of arch. Safety 
factor 6. 


Nominal 

Depth. 

Effective 

Depth. 

R 

Weight 
of Arch 
per 

Square Foot. 

Span of Arch in Feet = I>. 

Inches. 

Inches. 

Pounds. 

3 

4 

5 

6 

7 

8 

6 

3.6 

27 

309 

162 

94 




7 

4.6 

29 

400 

213 

126 




8 

5.6 

32 

481 

262 

156 

99 



9 

6.6 

36 

580 

311 

186 

118 

77 


10 

7.6 

39 

670 

360 

216 

136 

91 

61 

12 

9.6 

44 

852 

460 

279 

180 

121 

82 


Net loads in pounds per square foot, i. e.. excluding weight of arch. Safety factor, 6. 
The formula for safe load used in computing the above table is as 
follows : 

W = 840 T- 

in which 

W = Safe load per square foot of arch in pounds. 

R = Rise or effective depth of arch in inches. 

L = Span of arch in feet. 











































































82 


STEEL CONSTRUCTION 


In the following table are given, in pounds per square foot* 
the weights of various materials used in floor and roof construction 

TABLE XVI. 


Weights of Materials in Floor and Roof Construction. 


SUBSTANCE. 

AVERAGE WEIGHT IN 
POUNDS 

PER SQUARE FOOT. 

Corrugated galvanized iron, No. 20 

21 

Copper, 16-oz.—Standing seam 

n 

Glass, | inch thick 

31 

Cinder-concrete filling, 2-inch, including screeds 

12 

Plaster, on wood lath (no furring) 

6 to 8 

Plaster, on metal lath (no furring) 

8 to 10 

Plaster ceiling, suspended 

15 to 20 

hoofing felt, 2 layers 

* 

Slate, £ inch thick, 3 inches double lap 

4 ! 

Shingles, £ to weather 

2 

Gravel composition roof, 5 plv 

Oto 11 

Tin, 1 X 


Tiles, 6| in. X 10| in. — 5J in. to weather (plain) 

17 

Tiles, 10£ in. X 14£ in. — 7\ in. to weather (Spanish) 

9 

Trusses — Spans under 50 feet 

3g to 4 J 

Trusses — Spans 50 to 75 feet 

4‘ to<H 

Trusses —Spans 75 to 100 feet 

6£ to 8 


PARTITIONS. 

Partitions are of terra cotta, wire lath and plaster, and plaster 
board. 

Illustrations of each are given by Plate VI, Figs. 71 to 77. 
The element of strength does not form a specially important con¬ 
sideration here, as the standard forms are all suitable. The higher 
the partition the thicker should be the blocks or the heavier the 
metal frame of the partition. Some of the forms are more sound¬ 
proof than others and probably more fireproof, but the use of any 
one is generally determined by architectural conditions. The terra 
cotta blocks come in standard sizes given by the table below, which 
also gives the dead weight per square foot. The constructions 
around openings in partitions, for the different types of partition* 
are also shown by the above-mentioned cuts. 

Partitions are never as fireproof as the floor system in a build¬ 
ing. If a form of construction could be used which would prevent 
the spread of fire through partitions, the modern office building 
would probably be in truth absolutely, instead of merely in name" 










STEEL CONSTRUCTION 


83 


Plate VI 


"stee/ rod) 


Types of Fireproof Partition Construction 

- rouc/h frame^ 



S* : r ; YL: <?■: 

.v -‘. V f : 









fe 

KrJS3»t*6| 








r/o /S Ga/■ !/V/re /- ac/rrq 


Fig 71. 




ROEBLlKiG 4IN. WIRE LATH SOLID PARTITION 


f'sfee/ rod) _ 

./} • P/aihzr ;' • ; 


roc/g// frame 
■ Furring for baseboard 



6fap/e 


nU>s 




fYo/d G-a/ W/reLacmy 
Fig.7^ 

ROEBLING 2IN. WIRE LATH SOLID PARTITION. 


Channel } /* /x 7i 2 ^ 



BLOCK PARTITION. BLOCK PARTITION. 

fireproof. Tlie great cause of the weakness of fire resistance lie3. 
not in the partitions themselves so much as in the fact that open¬ 
ings for doors, windows, flues, etc., have to be made in them. The 
arrangement in a great many buildings makes it necessary, in order 
to give light in the corridors, to have a line of windows in the 
partitions between them and the offices. In addition there are the 




















































84 


STEEL CONSTRUCTION 


doors into the corridors, and the doors and sometimes windows in 
partitions, between offices. 

As stated under “Building Laws and Specifications,” some 
cities require in buildings of a certain height the use of metal or of 
- fireproof wood for all inside casings and finish, but in the majority 
of buildings these are not used. Sometimes, also, where plaster and 
wire lath partitions are used, the plaster does not extend to the floor, 
and the baseboard has therefore no fireproof protection back of it. 

All these features indicate the real elements of weakness in a 
fireproof partition, and on the extent to which they can be elim 
mated depends the utility of the partition as a fire barrier. As 
will be shown later under the paragraphs on tests, there are a 
number of forms of partition that can be used, which, if without 
openings and the other features mentioned above, will form effec¬ 
tual barriers. The extent to which fireproof wood and metal over¬ 
come the difficulties will be discussed farther on. 

Tests of Partitions. Numerous fire and water tests of 
partitions have been made by 4 ne New York Building Department. 
The partitions were of four general classes:—(1) plaster blocks; 
(2) blocks of cinder concrete; (3) wire lath plastered with King’s 
Windsor cement; (4) blocks of terra cotta. The partitions were 
21 inches and 3 inches thick. All were exposed to as nearly the 
same conditions as possible, which were :—a temperature gradually 
increasing from 500° to 1,700° during a period of one hour, and 
then a stream of water applied for 21 minutes. Fire in no case 
passed through any of the structures; but in the case of most 
of the plaster block partitions the blocks were calcined slightly in 
certain places, and the water had washed portions away to a depth 
of 1- inch to 1| inches. 

The wire lath parti ions did not show calcination, but showed 
to a greater or less extent the effect of the water in the washing 
away in spots of the browning coat and scratch coat, and, in some 
instances, in exposure of the lath or metal supports. 

The cinder-concrete blocks showed no effect of either fire or 
water, except that the plaster on the blocks was stripped off. 

The terra cotta blocks stood much the same as the concrete, 
no effect appearing in the partitions themselves, but the plaster 
being stripped off. 




STEEL CONSTRUCTION 


85 


The chief differences, therefore, seemed to appear in the capac¬ 
ities of the various types of partition to withstand the force of 
water. Those partitions having a harder and less porous structure 
stood much the best. 

From a consideration of the above tests, it will be seen that 
some forms of partition, under certain conditions of exposure in 
case of fire, will prove to be more difficult than others to repair, 
even though they may not entirely fail. Plaster, constituting the 
finish surface, could not be expected to stand, and does not in 
a severe fire; the expense, therefore, of this item in the repair 
would be essentially the same in all forms of partition. 

With some of the plaster board partitions in which the blocks 
were hollow, the calcination and the stream of water broke through 
the outer shell, leaving the cells exposed. In such cases it would 
probably be necessary to provide new blocks, as the old ones could 
not well be repaired. In the solid plaster board blocks the wear, 
if not more than | inch, could probably be repaired by hard plas¬ 
ter, so that, although not being as good as it was originally, the 
partition, in case of another fire, would still be considered reason¬ 
ably safe. 

The wire lath partitions cannot be considered fireproof until 
they are plastered. Here, accordingly, the plaster forms an essen¬ 
tial feature of the partition; and in case of any considerable 
portion of this being destroyed and exposing the metal frame, the 
partition could be repaired by replastering, provided the metal 
frame had not been injured. 

The concrete blocks and the terra cotta blocks in the tests 
cited above were not injured by the fire and water test; and so, if 
the results under actual conditions were always as favorable as in 
these artificial instances, th,e expense of repairing this form of par¬ 
tition would appear to be less than in the case of the other forms. 
It should be noted, however, that the partitions tested were with¬ 
out openings, and that openings in a partition weaken its lateral 
stability. While the block partitions were uninjured, they might 
not show so favorable results where openings occur, because of the 
attendant loss of lateral strength. In this respect it is probable 
that the plaster and wire lath partitions, and those plaster board 
partitions having metal stiffening, would not be any more liable to 




86 


STEEL CONSTRUCTION 


failure with openings than without, because, as constructed, the 
metal frame is secured at floor and ceiling, and, where openings 
occur, the frame is also tied longitudinally. 

Column Coverings. The particular form of covering to be 
used is affected by the section of the column. In general, how¬ 
ever, this consists of terra cotta blocks, wire lath, and plaster, or 
a solid block of concrete or plaster. As before stated, the princi¬ 
pal source of failure in all forms of covering is their liability to 
crack off or be knocked off. The more nearly, therefore, the cov¬ 
ering can approach a monolith of substantial thickness, the better 
it will be. If it consists of blocks, these should be bonded or 
anchored so as to tie the whole together, and should be made 
with one and preferably two air spaces. If of plaster on wire 
lath, it should be cement of sufficient thickness ; and if of concrete, 
cast in place, it should form a solid casing without joints and 
with an air space between it and the steel. In many cases, pipes 
are run in the column enclosure, so that in such instances the solid 
monolith is not practicable. 

Corrosion of Steel. An important feature in all .concrete- 
steel systems is the effect of the concrete on the steel. Some 
authorities have held that, on account of its alkaline nature, the 
presence of Portland cement in concrete is sufficient to prevent 
any corrosion of the steel. Observations of actual structures, and 
tests specially conducted, have shown, however, that under cer¬ 
tain conditions steel will rust when imbedded in Portland cement 
concrete, while under certain other conditions it will not rust in 
such an environment. It has been held by some, for example, 
that this rusting will not occur unless sulphur is present in the 
concrete. 

Professor Norton of the Massachusetts Institute of Technology 
has conducted a series of tests to observe the conditions under 
which steel in concrete will corrode. A number of mixtures of 
concrete were used, consisting of standard brands of cement and 
of both cinders and stone. The cinders showed very little sulphur 
present, and the concretes were distinctly alkaline. The metal 
imbedded was in the form of steel rods, sheet steel, and expanded 
metal. The results showed that when neat cement was used no 
corrosion occurred. It was also demonstrated that when corro- 



STEEL CONSTRUCTION 


87 


sion occurred in either the cinder or stone concrete, it was coinci¬ 
dent with cracks or voids in the concrete which allowed the 
moisture and carbon dioxide to penetrate. If the concrete was 
mixed wet, so as to form a watery cement coating over all the 
steel, this coating protected the metal even when cracks and voids 
were present. 

Professor Norton announced the further conclusion that when 
rusting occurred in cinder concrete it was due to the iron oxide or 
rust in the cinders, which acted as a carrier of the moisture and 
carbon dioxide, and it was not due to the presence of sulphur. 
Also, that if cinder concrete was well rammed when wet, and was 
free from voids, it was about as effective as stone concrete in 
preventing rust. 

His conclusion as regards the part played by rust in itself 
aiding the further corroding action by assuming the role of carrier 
for the active agents, shows the importance of having the steel 
free from rust when it is imbedded in the concrete. 

The above observations and conclusions are of the utmost 
importance as establishing the conditions under which, in both 
stone and cinder concretes, steel may reasonably be expected not 
to corrode, and as showing clearly the precautions and methods 
that should be observed in such construction. 

Paints. Paints used for the protection of steel, consist, 
like all other paints, of a pigment and a vehicle. The pigments 
used are generally red lead, iron oxide, carbon, and graphite. The 
vehicle commonly used is linseed oil; and generally this is boiled 
oil, although raw oil is sometimes used. 

Observations covering a period of about four years were made 
by Mr. Henry B. Seaman, Member of the American Society of 
Civil Engineers, on various kinds of paint exposed to the locomo¬ 
tive smoke and gases on viaducts over the Manhattan Elevated 
Railroad in New York City. His report, published in the New 
York Evening Post , concludes that carbon and graphite paints 
stand such exposure rather better than others, and the carbon 
paints somewhat better than the graphite. None-was entirely 
efficient. A detailed paper on paints for steel was prepared by Mr. 
G. M. Lilley, Associate Member of the American Society of Civil 
Engineers, and was published in Engineering News, April 24, 1902. 



88 


STEEL CONSTRUCTION 


The value of paints as agents in the prevention of rusting of 
steel depends much upon the conditions under which the painting 
is done, the quality of the paint, and the treatment of the metal 
after painting. 

The experiments of Professor Norton, already mentioned, 
have established that the essential thing is a coating of the steel 
which will not crack or peel off and is non-porous, and that the 
steel must be clean. The fact that in many cases paint has been 
applied over a coating of rust, does not, of course, afford any reason 
for condemning the use of paint because of its failure in such cases 
to prevent further corrosion. 

If the paint can be applied in such a way as to form for the 
steel a continuous coating that will not crack, or blister, or peel 
off, it will probably be a very effective preventative of rust. All 
paints, however, are more or less porous, and to this extent 
inefficient. 

It is, however, the opinion of the authorities who have given 
this subject most study, that, while more expensive, a thin coating 
of Portland cement applied continuously to a clean surface of 
steel is more effective than paint. 

The alkaline character of the cement neutralizes the carbon 
dioxide which may be present, or which may tend to filter through 
to the steel. In this regard, therefore, it is probable that a small 
degree of rust in the steel before it is coated with cement would 
not be likely to cause further rust, as would be the case if the coat¬ 
ing were of ordinary paint, since the carbon dioxide present in the 
rust would be neutralized by the cemeftt. 


FIRE-RESISTING WOODS. 

There are several companies who have processes of treating 
wood to render it fire-resisting. These processes differ materially. 
None of them renders the wood absolutely fireproof, and tests 
have conclusively established that all such treated woods will burn 
if subjected to sufficient heat for a considerable time. Some 
authorities place this temperature limit at which ignition will 
occur, as low as 100° above the temperature required to burn 
untreated wood. Other authorities claim that the period during 






STEEL CONSTRUCTION 


89 


which wood will glow after it has been ignited and the flame 
removed, is as 1 to 10 for the treated and the untreated woods 
respectively. 

The process of treating woods is to impregnate them with 
certain chemicals which serve to retard the giving off of combus¬ 
tible gases by the wood under heat, and which also, under the 
action of heat, themselves give off certain other gases that serve 
to extinguish combustion when started. 

It has undoubtedly been demonstrated that treated wood will 
burn, and that the gases from it are combustible. It is, however, 
equally well established that treated wood will not ignite as readily 
as untreated wood; that it requires a higher temperature to main¬ 
tain its, combustion; and that when the source of heat is removed 
the wood will cease to glow more quickly than untreated wood. 

A material has recently been put on the market in England 
under the name of “Uralite,” which, it is claimed, can be worked 
like wood ; and can be used largely in the same way, that is, either 
solid or as a veneer to form a fireproof covering. The basis of the 
material is asbestos mixed with whiting. The finished material is 
made of several thin layers felted together. For a description of 
this material, see Engineering , August 15, 1902. 





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STEEL CONSTRUCTION. 

PART II. 


BEAMS AND GIRDERS. 

Determination of Loads. The first step in the calculation 
of a beam or girder is to determine the exact amount of load to be 
carried, and its distribution. Loads may be uniformly distributed 
or concentrated, or both in combination. The case of a simple 
lloor or roof beam usually involves only the calculation of the area 
carried and the load per square foot. The load per square foot 
is made up of two parts—namely, dead load, or the weight of the 
construction; and live load, the superimposed load. The latter 
is generally specified by law, as noted previously under “ Building 
Laws and Specifications.” 

The calculation of the dead load has to be made in detail to fit 
each case. In the case of a floor beam this would consist of the 
arch between the beams, the steel beams and girders, the filling on 
top of the arch, the wood or other top flooring, the ceiling, and the 
partitions. These weights cannot be accurately determined until 
the spacing and size of beams are fixed; so their features have 
to be assumed at first. The process in general is illustrated by the 
following case: 

Assume a terra cotta arch 8 inches deep, beams spaced about 

5 feet center to center, 3 inches of filling and screeds on top of the 

arch, a |-inch hemlock under floor, and a li-inch oak top floor. 

The weights then are as follows: 

8-in. arcli = 30 lbs. 

Steel = ~ = 3.6, or say = 4. “ 

5 

Filling = 3X5 = 15 “ 

|-in. floor = | X 2, say = 2 “ 

1| -in. top = 1.125 X 3.67, say = 4 “ 

Ceiling (no furring) = 7 “ 

Partition == 64 “ 

5 

Total Dead Load 


126 lbs. 




92 


STEEL CONSTRUCTION 


The calculation of- the dead weight per square foot of parti¬ 
tions is made up of the weight of blocks, if of terra cotta, and 
of the plastering on both sides. If the structure is of wire lath, 
the weight is that of the framing and plastering. These weights 
per square foot have already been given in the chapter on Fire¬ 
proofing. 

Only the height of the story is used, as the partition stops at 
the ceiling. In the above case it is assumed that the partition 
may go anywhere, and therefore, in some cases, may come directly 
over a beam, thus being entirely carried by it. If the partitions 
are in general located so as to come between beams, and no pro¬ 
vision is desired for other possible locations, the above partition 
load might be reduced one-half, as a partition would then be carried 
by two beams. Or if the partitions came only over girders, the load 
might be omitted entirely in the calculation of the beams. 

In the above total dead load, it should be noted that the allow¬ 
ance for steel does not include the weight of girders. This of 
course should not be included for the beams. In the calculation 
of the girders the weight of the girder itself should be added. 

The calculation of dead load cannot be absolutely exact, any 
more than can the determination of the exact amount of live load 
that will have to be carried. It should always, however, be worked 
out in detail as above, so that as close an approximation as possible 
shall be made. 

Tables XIV and XVI, of Part I, and Table XVII, Part II, 
give the weights of different materials and forms of construc¬ 
tion, for use in determination of dead loads under different con¬ 
ditions. 

The floor arch is assumed to carry all its load vertically to the 
beams, and the load therefore is the product of the area and the 
load carried per square foot. This neglect of thrust from the arch 
is on the safe side as regards the determination of amount of load 
on the beam. 

Distribution of Loads. The load on a girder is generally 
concentrated at one or more points, and involves the calculation 
of the reactions from the beams. Girders therefore, as a general 
thing, are not calculated until after the beams. A girder may also 
have a uniform load from one side, or from a partition or wall. 



STEEL CONSTRUCTION 


1/3 


TABLE XVII. 

Weights of Various Substances and Materials of Construction. 


SUBSTANCE. 

AVERAGE 

WEIGHT IN 

POUNDS PER 
CUBIC FOOT. 

Aluminum 

162 

Ash 

38 to 47 

Asphaltum 

62 to 112 

Brass (cast) 

490 to 525 

Brick 

100 to 150 

Brickwork 

100 to 140 

Cement, Portland 

80 to 110 

Cement, Rosendale 

55 to 65 

Cherry 

42 

Chestnut 

41 

Clay, Potter’s, dry 

112 to 143 

Clay, in dry lumps 

65 

Coal — Anthracite 

52 to 60 

Coal — Bituminous 

47 to 52 

Coke 

Concrete — Stone and 

23 to 32 

Portland cement 
Concrete — Cinders and 

140 

Portland cement 

96 

Copper, cast 

542 

Copper, rolled 

555 

Cypress 

Earth — Common loam, 

64 

dry and loose 

Earth — Common loam, 

72 to 80 

dry and rammed 

Earth—Common loam, 

90 to 100 

soft-flow T ing mud 

110 to 120 

Elm 

35 

Gneiss, common 

Gneiss, in loose piles 
Gold, cast pure or 24 

168 

96 

knrat 

1,204 

Gold, pure-hammered 

1,217 

Granite 

160 to 178 

Gravel 

90 to 130 

Hemlock 

25 


SUBSTANCE. 


or 


or 


Hickory 
Iron, cast 
Iron, wrought 
Lead, commercial 
Limestone 
Lime, quick 
Mahogany 
Marble 

Masonry, granite or 
limestone, dressed 
Masonry, granite 
limestone, rubble 
Masonry, granite 
limestone, dry rubble 
Masonry, sandstone | 
less than above 
Mortar, hardened 
Oak, live 
Oak, white 
Oak, red 
Pine, white 
Pine, yellow Northern 
Pine, yellow Southern 
Poplar 
Platinum 
Quartz 
Sand 

Snow, freshly fallen 

Snow, moist compacted 

Slate 

Spruce 

Steel 

Sycamore 

Tar 

Terra Cotta 
Terra Cotta masonry 
Tin, cast 


AVERAGE 
WEIGHT IN 
POUNDS PER 
CUBIC FOOT. 


53 

450 

480 

710 

153 to 178 
95 

35 to 53 
158 to 180 

165 

154 
138 


87 to 112 
60 
47 

32 to 45 
25 
34 
45 
29 
1,342 
165 

90 to 130 
5 to 12 
15 to 
175 
25 
490 
37 
62 
106 
112 
459 


50 


Note. Where weights of wood are given above they are for perfectly dry 
wood. Green timbers weigh from one-fifth to one-half more than dry, ordi¬ 
nary building timbers, one-sixth more than dry. 
























94 


STEEL CONSTRUCTION 


thus bringing sometimes very unsymmetrical loading. Openings 
also affect the distribution of loading on a beam or girder. 

Stairs should be figured as fully loaded with the assumed live 
load and the dead weight of their own construction, and as being 
supported by the girder on which they rest. In the case of very 
heavy live loads, as in warehouses, the customary live load in 
office buildings could be used in determining the load for stairs. 

If the framing plan is drawn accurately to scale, the position 
of concentrated loads can be determined by scaling. In the case 
of short girders with heavy loads, however, a slight error in deter¬ 
mining the position of loads would appreciably affect the result; 
hence it is necessary to exercise caution in scaling the position, to 
avoid any chance of great variation from true measurement. 

Beams and girders carrying elevator machinery should have 
the loads and their position determined with special care. To 
this end the layout of the company installing the machinery 
should always be used in final calculation. This layout gives the 
loads at the different points; and therefore the exact position on 
the supporting beams, and the reaction on the girders, can be 
determined. As elevators are liable to cause a shock in sudden 
starting and stopping, it is customary to multiply the total load by 
two to allow for this shock. 

In the calculation of the girder the laws of some cities allow 
a reduction amounting to a certain percentage of the live load, on 
the assumption that the whole area adjacent to a girder is not 
likely to be loaded to its maximum at the same time. This, how¬ 
ever, should not be done in warehouses, nor where on the other 
hand the assumed loads are very light; and in any case it should 
be done with discretion. 

Lintels. The size and character of lintel beams depends (1) 
on load to be carried, (2) on arrangement of openings over beams, 
(3) on practical considerations of construction. 

If the wall is solid above the opening for a height greater 
than the span of the opening, the masonry, if of brick, will arch to 
some extent and thus relieve the lintel of a portion of the load. 
Practice varies in the proportion of load assumed to be carried. 
It is good practice to consider the weight of a triangular section of 
wall, of height equal to the span, as carried by the lintel. If 



STEEL CONSTRUCTION 


95 


there is only a small pier under the ends of such a lintel, however, 
this arch effect should not be considered, but the full load of 
masonry provided for. In very wide openings, also, the full load 
should be calculated on the lintel. The basis for assumption of 
arching effect is that brickwork can be corbeled out at an angle of 
about 60°, and support safely its own weight after final set in the 
cement has taken place. This assumption should not be made 
where the center of gravity of such mass of masonry will fall out¬ 
side the supporting base. The figures below will illustrate this 
principle. 

Another assumption sometimes made is, that the wall span¬ 
ning the opening is capable, as a beam, of carrying a certain por¬ 
tion of the load, and that the lintel need be calculated only for the 
additional weight. This is necessarily dependent on the tensile 
strength of the mortar joints, which, although being considerable 
in an old wall, would be very slight in a new wall; and for new 
work, therefore, this assumption should not be made. 

The arrangement of openings 
above the lintels often makes it 
necessary to provide for the full 
load of wall, because this load is 
carried in the direct line of piers 
to the lintels. Such cases are 
illustrated by the figures below. 

The particular form of lintel 
will depend not only on the load, 
but on the way in which the metal 
must be distributed in order to 
carry the load. A very thick wall 
may necessitate a number of beams 
or other shapes to provide neces¬ 
sary width on which to lay the 
brickwork. If the stope or terra 
cotta facing has to be supported, 
this also necessitates special shapes 
to meet the requirements. More¬ 
over, if floor loads are to be carried, the size and shape will be 
largely fixed by this further condition. A lintel may, therefore, 


-l- 


Fig 73 

















96 


STEEL CONSTRUCTION 


consist of a number of different shapes of different sizes. The 
problems below illustrate types of condition ordinarily met with. 

Beam Plates. Beams and girders carrying ordinary loads, 
usually have plates under the ends resting on the walls, in order 
properly to distribute the load on the masonry. 

The method of determining the proper size and thickness of 
such plates is as follows: 

In Fig. 78, l — dimensions of plate in inches transverse to 


web of beam; 

b ' — dimension of plate in inches in direction of 


web of beam; 

b — width of flange of beam. 


The plate should cause the load to be uniformly distributed on 
the masonry over its whole area. 


If R == the reaction at wall end, 

R 

then jr~j — the load per square inch on masonry. 


The portion of the plate not covered by the flange of beam is 
in the condition of a beam fixed at one end and free at the other. 
The formula for the moment, therefore, is: 


M = i p L* 


V = p~i * and 


R , r l-b 

jj-j , and Lt — 7c 


R 

therefore M = | X ^ X 



considering a strip 1 inch in direction of web of beam; but from 
the formula for beams, 



z=z l f b t 2 : then, since y = 



STEEL CONSTRUCTION 


97 


therefore 


6 M ■ . , R (7-6) 6 

~f~b ~ t = I * j/~i X ~ 4 — Xy, since b = 1, 


which reduces to £ 2 = -r 
4 


R(7—6) 2 
~~VTf 


t = .866 

For steel plates,/= 16,000 
For cast iron f = 2,500. 

The safe bearing on masonry has been specified in the chap¬ 
ter on Building Laws and Specifications. 

If two or more beams spaced close together were used, then b 
in the above formulae would be the extreme distance between 
flanges of outside beams. 

Anchors. Beams resting on brick walls are anchored to 
these walls. Some of the more common forms of anchors are 
shown by Figs. 79 to 86. 

Separators. When two or more beams are used together to 
form a girder, they are bolted up with separators. These sepa¬ 
rators are either bolts running through spool shaped castings 
of the required length to fit between the webs of beams, or 
plate-shaped castings made to fit accurately the outlines of 
the beams and having width equal to the space between webs 
of beams.. The object of these separators is two-fold; (1) to pre¬ 
vent lateral deflection of the beams under the loading; (2) to dis¬ 
tribute the loads equally between the beams when the loads are 
not symmetrical on the two beams, and to cause the beams to de¬ 
flect equally. The latter function is by far the more important 
one, and for this purpose the second form of separator is the only 
one that should be used. Beams over 12 inches deep have, as a 
general thing, two horizontal lines of separators; beams under 12 
inches, one horizontal line. 

Figs. 87 to 89 illustrate the different types of separator. 

Calculations. To find the actual fibre stress on a given beam 
supporting known loads : 






98 


STEEL CONSTRUCTION 




Data required: 

1. Length of span of beam, center to center. 

2. Size and weight per foot of beam. 

3. The amount and character of load on the beam. 



Fig. 65. 














































































































STEEL CONSTRUCTION 


99 


Operations: 

1. Find from the tables in Cambria the moment of in¬ 
ertia of the beam. 

2. Figure the bending moment due to all the concentrated 
loads, and the uniform load in inch-pounds. 


3. 


M y 

Apply formula / = j—. 


Substituting the values obtained above we find the value of/. 


Note. Since we know the size of beam, the value of y is one-half the 
depth of beam. 



4 §==§ 


m=m 


Fiq. 67 

CAST IRON SPOOL SEPARATORS 


A more direct method would be to find the Value of S (see 
Cambria) and dividing M by S which would give the required 
fibre stress. 




Rg. 66 

STANDARD CAST IRON SEPARATOR WITH ONE BOLT 


To find what load , uniformly distributed , will be carried by a 
given beam at a given fibre stress. 

Data required: 


1. Length of span, center of bearings. 

2. Allowed fibre stress. 

3. Size and weight per foot of beam. 




































100 


STEEL CONSTRUCTION 


Operations: 

1. Find from the tables the moment of inertia of the 
given beam. 

2. Find the value of the beam in bending-moment, 

/ I 

inch-pounds, from the formula M = — 

3. Find the value of the beam in bending-moment foot¬ 
pounds by dividing the result obtained under operation 2 by 12. 

4. Find the value of W in the formula 


W = 


8 M 


in which W — the total load in pounds uniformly distributed 
which the beam will support: 

M — the bending moment in foot-pounds ; and 
l = length of span in feet. 


T 


°> t| 

= 3 = 

] 

li 

A 


o) t 

=5H 

] 

1 N- 
\\§ 

X 


Fig Q9. 

STANDARD CAST IRON SEPARATOR WITH TWO BOLTS . 


To find the size of beam required to carry a system of known 
loads at a given fibre stress. 

Data required : 

1. Length of span, center to center. 

2. Allowable fibre stress. 

3. The amount and character of load on the beam. 
Operations: 

1. Figure the bending moment in inch pounds due to 
all the concentrated loads, and the uniform load. 















STEEL CONSTRUCTION 


101 


2. Divide the bending moment in inch pounds by the 
specified fibre stress, and the result will be the required section 
modulus, S. 

3. Select from Cambria a beam having the required 
value of S. 

* Note. Due attention in selecting the beam must be given to lateral 
and vertical deflection as previously noted, or to a proper reduction of the 
specified fibre stress to allow for these considerations. 

PROBLEMS FOR PRACTICE. 

1. Given a 15-inch 60-lb. beam on a span, center to center 
of bearings, of 22 feet 6 inches. Required the safe load uniformly 
distributed at a fibre stress of 16,000 lbs. per square inch. 



Fig. SO 


Solve (a), by the methods given above; 

(6), by use of coefficient of strength given in table of 

C 

Properties by the formula M = g. 

2. Find from the table of Safe Loads the total load, which 
a 6-inch 12.25-lb. beam will carry on an effective span of 15 feet, 
without exceeding the limits of deflection for plastered ceiling; 
allowable fibre strain 16,000 lbs. per square inch. 









































102 


STEEL CONSTRUCTION 


What would be the safe load in the above problem if the 
allowable fibre strain were 10,000 lbs. per square inch? 

In the following problems, solve, 

(a) by use of tables of Safe Loads, and 


(5) by formula M =*^, and use of table of Properties. 

3. Find the greatest safe load in pounds uniformly distrib¬ 
uted that will be sustained by a 10-inch 35-lb. I beam having a 
clear span of 10 feet 3 inches and an effective span of 11 feet 3 
inches, the allowed stress in extreme fibre being 12,500. 

4. The moment of the forces in * 

foot-pounds acting on a beam of un¬ 
determined size is 108,000. What size 
of beam will be required if a stress of 
16,000 pounds per square inch is allowed 
in extreme fibre ? 

5. What load uniformly dis¬ 
tributed will a 15-inch 42-lb. I beam 
support per linear foot, if the span, cen¬ 
ter to center of bearings, is 10 feet 4 
inches, and the allowed stress in ex¬ 
treme fibre is 14,500 pounds per square 
inch? 

6. What weight of wall will a 
12-inch 81.5-lb. I beam 18 feet long be¬ 
tween center of. bearings carry, no 
transverse support for wall? Allow¬ 
able fibre strain, 16,000 lbs. per square 
inch. 

7. An office building has columns 
spaced 15 feet on center ‘in both direc¬ 
tions. Give in detail the estimates of dead load for the following 
constructions. Live load in each case 100 lbs. per square foot. 




LINTELS TYPE B. 
Fig 91 


(a) Beams spaced 5 feet center to center, 8-incli terra cotta arch of end 
construction, 2-inch wood screeds and cinder concrete filling, g-incli under 
floor, and £-inch maple top floor. 

(b) Same conditions, except 8-inch terra cotta arch of side construction. 

(c) Same spacing of beams, with expanded-metal arch, type 8. 












STEEL CONSTRUCTION 


103 


(d) Same conditions as above, but expanded-metal arch, type 3, with 
suspended ceiling. 

(e) Beams spaced 7 feet 6 inches center to center. Columbian system, 
type 2, stone concrete. 

Note. In all above cases, partitions are of 3-inch terra cotta blocks, 
and come only over girders. Clear story height = 10 feet. Give loads for 
both beams and girders. 

8. Required a lintel over opening shown by Fig. 92. 
Clear span 15 feet, wall 16 inches thick and 50 feet high. No 
floor or any load carried by wall. 

In this type of opening, the narrow piers or columns under the lintels 
make it necessary to figure the full load of wall, as otherwise the narrow 
base supporting the heavy overhanging mass of masonry would cause at the 
piers a thrust that would necessitate continuous tie rods. The full load, there¬ 
fore, would be 50 X 15 X 1 33 X 115= 115,000 lbs. The effective span of lintel 
is 16 feet; the capacity of two 18-inch 55-lb. I beams for this span is 117,800 
lbs., and these would, therefore, be the required sections. 



LINTELS, TYPE C. 
Ftq 92 


Required the size of lintel of type B, Fig. 91. Span between 
centers of bearings, 7 feet. Wall 20 inches thick. Floor load 
200 lbs. per square foot. Columns spaced 15 feet from wall. 

In this case the piers at side of opening are sufficiently heavy for us to 
consider the wall over opening as arching, as shown by dotted lines. 

Floor load = 200 X 7.5 X 7 = 10,500 lbs. 

Wall load =7 X 3.5. X 1.67 X 115= 4,697 lbs. 


The full floor load should be provided for. The wall load is not a uniformly 
distributed load, and moment should be calculated by assuming load 
between center and end of girder as acting £ the way from the center of the 


girder. 

M of floor load= | X 200 X 7.5 X 7 X 7 X 12 
M of wall load = 7 X 3.5 X 1.67 X 115 


= 110,200 


X 2.33 X 12 = 65,500 

1757700 


inch-pounds. 


t i 


u 

<( 


2 


it 



























104 


STEEL CONSTRUCTION 


The moment in foot-pounds of wall load can be obtained also by the use 
n I s 

of the formula M = "—where p is the weight of a square foot of the masonry 

of the given thickness, and l the span. 

If the allowable fibre strain is 16,000, this gives a necessary section 
modulus of 11.0. 

Two 7-inch 9.75-lb. I beams have a total section modulus of 12,0, and 
would, therefore, be sufficient. 

Note. In this calculation the strength of the angle riveted to the chan¬ 
nel is not considered in the capacity of lintel. 

10. What size of beam will be required to span 19 feet cen¬ 
ter to center of'bearings, and support a uniform load of 1,200 lbs. 
per linear foot, together with two concentrated loads of 5,000 
pounds each ? One concentrated load to be applied 7 feet from 
the left-hand support and the other 8 feet 9 inches from the left- 
hand support. The allowed fibre stress is 9,000 pounds per 
square inch. 

11. Find the actual stress in extreme fibre of a 12-inch 31.5- 
lb. I beam spanning 12 feet 6 inches center to center of bearings, 
and supporting a uniformly distributed load of 23,500 pounds, and 
one concentrated load of 7,500 pounds placed 4-feet 9 inches from 
left-hand support. 

12. What will be the most economical arrangement of floor 
beams and girders for carrying a load of 175 pounds per square 
foot, including weight of floor? Assume floor to be of expanded 
metal, fireproof construction, and beams spaced not to exceed 6 
feet. Under side of floor to carry a plastered ceiling. 

13. What size and weight of beam, 23 feet long in the clear 
between walls, will be required to carry safely a uniformly dis¬ 
tributed load of 14 tons, including the weight of beam? 

14. What load uniformly distributed, including its own * 
weight, will a 12-inch I beam, 31.5 pounds per foot, carry for a 
clear span of 23 feet 6 inches, without deflecting sufficiently to 
endanger a plastered ceiling? Beams rest 12 inches on walls at 
each end. 

15. Calculate by use of Cambria book the moment of ineitia 
about the neutral axis perpendicular to web at center of a 12-inch 
31.5-lb. beam. 

16. Given a girder loaded as follows: Effective span 28 
feet; center load 4,000 lbs.; and a load, 7 feet each side of cen- 



STEEL CONSTRUCTION 


105 


ter, of 3,000 lbs. Required the size of beam such that the deflec¬ 
tion will not exceed plaster limits. 

IT. Given a warehouse 180 feet by 80 feet inside of walls. 
Columns spaced 18 feet longitudinally and 16 feet transversely. 
Total load per square foot 300 lbs. Required the necessary sizes 
of beams and girders. 

18. In the above warehouse, what changes in -spacing of 
columns longitudinally could be made to give more, practicable 
sections of beams and girders, and what sizes could then be used? 

19. Given a girder loaded as shown by Fig. 93. Allowable 
fibre stress, 16,600 lbs. per square inch. Required: 

(a) The size of single beam girder. 

( b ) The size of single beam or channel to carry end of girder 
framing into lintel. 

( c ) The size of double beam girder. 

( d ) The size of double beam or channel lintel. 



20. Given a system of overhead beams for an elevator as 
shown by Fig. 94. Required the size of beams Nos. 1, 2 and 3. 
Make allowance for shock as previously stated, and observe that 
when two .beams are used together as a girder they must be of the 
same depth. Allowable fibre stress 15,000 lbs. per square inch. 

In all the above problems, unless otherwise noted, use / — 
1,600 pounds per square inch. 

COLUHNS. 

. A column ordinarily has to carry only vertical loads. There 
are conditions in which it has to resist lateral forces, but these will 









































106 


STEEL CONSTRUCTION 



Fig. U4. 


be taken up under the heads of “High Buildings” and “Mill 
Buildings.” 

Shapes Used. A column may be made of any of the struc¬ 
tural shapes that are rolled, or of any combination of them which 
it is practicable to connect together. In practice, however, there 
are certain combinations which are commonly used to the exclu¬ 
sion of others. Beams, channels, angles, tees, and zees are all 
used singly at times, as columns. The more common combination 
of shapes are shown in Plate I of Part I. 






















STEEL CONSTRUCTION 


107 


The component parts of these columns will be evident in 
most cases, from an inspection of the figures. The white spaces 
between the black lines indicating the different shapes do not 
represent actual spaces; this is a conventional form to more clearly 
show the shapes of which the column is composed. 

Fig. 5 is a two-angle and a four-angle column. Adjacent 
legs- of the angles are riveted together as indicated. Sometimes 
plates are riveted between the angles to increase the area of the 
column or to make simple connections. 

Fig. 6 is a four-angle column to which the angles are connected 
by lattice bars, which come in the position shown by the light line, 
and run diagonally from side to side of the column for its entire 
length. 

In Fig. 7 a continuous plate is substituted for the lattice bars. 

Fig. 8 is a similar column in which one or more plates are 
added to the outstanding legs, on each side, to increase the area 
of the column. 

Fig. 9 represents a column composed of two channels con¬ 
nected by lattice bars, riveted to the flanges. 

In Fig. 10 continuous plates are substituted for the lattice bars. 

Fig. 11 is a column similar to Fig. 10, but shows plates 
riveted to the webs of the channels to stiffen them and to increase 
the area of the column ; these "plates have to be riveted before the 
flange plates are put on. 

Fig. 12 is a column of similar shape, but instead of the 
channels, angles riveted to plates are used. This has the dis¬ 
advantage, common to Fig. 11, of four extra lines of rivets as com¬ 
pared with Fig. 10. A heavier section can be made, however, 
than would be possible with any of the channel sections, and a 
better riveted connection can be made through the flange angle 
than through the flanges of the channels. 

Fig. 13 is known as a “ Grey column,” and is a patented sec¬ 
tion. The unshaded lines between the angles represent tie plates 
which occur about 2 feet 6 inches apart from top to bottom, and 
serve to connect the angles to each other. 

Figs. 14 and 15 are similar to Figs. 9 and 10, the channels 
being simply turned in instead of out; this is of advantage some¬ 
times in making connections or when a plain face is desired. 



108 


STEEL CONSTRUCTION 


Fig. 16 is called a “ Larimer column,”'and is also a patented 
section. It consists of two I beams bent in the form shown and 
riveted together through a special shaped filler, shown unshaded. 
This column has the same advantage as the Grey column, that it 
gives a flange on all four sides to make connections with. Neither 
column is very generally used, however, and when used they are 
subject to a small royalty charge. 

Fig. 17 is a modification of Fig. 8, in which channels are 
used instead of plates. This gives more simple connections of 
beams, especially where the beams frame eccentrically with regard 
to the axis of the column. This section also gives a larger radius 
of gyration, and has many of the advantages of the Z-bar column 
shown by Fig. 23, although having four extra lines of rivets. 

Fig. 18 is a column having four Z bars connected by tie 
plates spaced about 8 feet apart, and which are indicated by the 
unshaded lines. 

Fig. 19 is similar except a continuous plate is substituted for 
the interior tie plates. 

Fig. 20 is a section intended to give the form of Fig. 17. 
The rivets through the beam flanges are objectionable, however, 
except for light loads and short lengths. 

Fig, 21 is a modification of Fig. 19, in order to increase the area. 

Fig. 22 is a modification of the usual form of Z-bar column 
shown by Fig. 28. Tins gives increased area and a greater spread 
between the outstanding flanges of the Z bars, which is of advantage 
sometimes in making connections. 

Fig. 28 is the very generally used Z-bar column. This 
section has its metal so distributed as to give a high radius of 
gyration, and its shape makes connections simple. Z bars cost 
about ^ of a cent per pound more than other shapes, and it is not 
possible, generally, to get so prompt delivery. 

Fig. 24 shows the usual method of increasing the area of a Z- 
bar column by adding plates to the flanges. 

Effect of Connections. In order to design a column intelli¬ 
gently, it is necessary to know in every case how the members 
that are to carry the load to the column are to be connected to it. 
Types of connection are illustrated by Plates YII and VIII, Fig^. 
95 to 105. 



STEEL CONSTRUCTION 


109 














































































































































































110 


STEEL CONSTRUCTION 






































































































































































STEEL CONSTRUCTION 


111 


There is hardly ever a case in which the loads on a column 
can he exactly balanced so that the center of gravity of the loads 
will coincide with the axis of the column. Practically, also,.the 
beams on one side may receive their full load while those on the 
other side are only partially loaded. The effects of eccentricity 



of loading are very apparent in tests of the carrying capacity of 
columns; and, where practicable, a column section should be 
chosen wdrich will admit of connections bringing the loads as near 
to the axis of column as possible. If the beams frame symmetric¬ 
ally about the axis of the column and are almost equally loaded, it 
is not generally necessary, in calculation, to consider the effect of 

































112 


STEEL CONSTRUCTION 


eccentricity. In cases, however, such as frequently occur in con¬ 
nections of spandrel beams and wall girders to columns, this eccen¬ 
tricity should be considered in the calculations. 

To facilitate the erection, connections of beams to columns 
should always be by a shelf having the proper shear angles under, 
rather than by side connections. Another advantage in this form 
of connection is that the deflection of the beam does not cause 
so much bending stress in the column. As will be seen from Fig. 
106, if a deep beam or girder were connected by angles in the 
web, a deflection in the beam would cause the top to tend to pull 
away from the column ; and, if the beam were held rigidly by side 
angles, considerable bending stress in the column would result. 

Selection of Sections. The particular form of column section 
will vary with the conditions. 

1. The first consideration is usually the amount of load; 
certain forms cannot be used without excess of metal if the loads 
are light; and conversely, certain other forms cannot be used 
economically if the loads are very heavy. 

2. The next point to be considered is the way the beams 
come to the oolumn. If the framing is symmetrical and on four 
sides, any of the sections could be used; in such a case, however, 
it would be simpler to avoid single or double angles for use as 
columns. 

If the connections are eccentric, then a section stronger in 
the direction of eccentricity should be chosen, and one that will 
admit of easy connections. If a heavy girder comes in on top of a 
column, then the metal must be specially arranged to meet this 
condition. The consideration of these points will be taken up 
and illustrated in detail under the head of “ Connections.” 

3. In the case of wall columns, the architectural details, — 
such as size of pier, relation to ashlar line, thickness of walls, etc., 
— by limiting the dimensions of column, generally affect the choice 
of form of section. 

4. Other architectural conditions, such as, shape and size of 
finished column, relations to partitions, provision for passage of 
pipes, wires, etc., have to be considered in the general choice, as 
it is desirable to adopt the same type throughout even if the limi¬ 
tations affect only certain columns. 



STEEL CONSTRUCTION 


118 


5. The condition of the steel market as regards delivery 
of certain shapes within the required time, is always a factor. 
A delay of several months may sometimes be saved by proper con¬ 
sideration of this point. 

Calculation of Sections. The type of column having been 
decided on, the calculation of sections is the next step. 

The effect of connections is as important in the case of cast-iron 
columns, as in that of steel columns, and typical details are shown 
in Plates X and XI, Figs. 108 to 111. 

Plate XII, Fig. 112, shows a cast-iron ribbed base designed 
for a square column similar to that shown by Fig. 110. 

Fig. 113 shows a cast-iron base designed for a steel column, 
the section of which is indicated by the hatched lines. An impor¬ 
tant feature of all cases of this type is to have the metal arranged 
so as to conform to the metal of the column that rests upon it. 

A good many designers give a slight pitch downward to the 
brackets forming the seats of beams. This is of advantage in 
avoiding the tendency, which would otherwise occur, of the beam 
to bear most heavily on the other edge when deflection under load¬ 
ing takes place. 

There are several types of column formulae in general use; 
and, as noted under “ Building Laws and Specifications,” there is 
a variation in the legal requirements of different cities in this 
respect. 

Gordon’s formula is perhaps the oldest and most generally 
used. This is as follows: 

„ 12500 

'=i+f 

ar 2 

where / = safe fibre strain reduced for length and radius of 
gyration ; 

l = unsupported length, in inches ; 
r = radius of gyration, in inches ; 
a = a constant, of the values below: 

= 36,000 for square bearing; 

= 24,000 for pin and square bearing 
= 18,000 for pin bearing. 




114 


STEEL CONSTRUCTION 


Plate X. 


Cast Iron Columns 





Fg/06 




Fig. 109. 























































STEEL CONSTRUCTION 


115 


Plate XI 



Cast Iron Columns 



Pig III 












































































































116 


STEEL CONSTRUCTION" 


The formula used by the Carnegie Steel Company for the 
calculation of capacity of Z-bar and box-section columns is as 
follows: 

/ = 12,000 for lengths of 90 times the radius of 

gyration. 

/ — 17,100 — 57 — for lengths greater than above. 
r 

Cooper’s formula is as follows: 

/= 16,000 — 58 i_. 

r 

This formula, while similar in form to the one used by the 
Carnegie Company for lengths above 90 radii, is applied by Cooper 
to all lengths. 

The American Bridge Company use the following formula 
for all lengths: 

17,000 

J 72 

1 4-_ 1 _ 

^ 11,000 r 2 

The results given by these formulae vary considerably, the 
variation increasing under certain conditions of length and of radius 
of gyration, and being greater with large values in ratio of length 
to radius of gyration. 

The student should work out the areas of column required 
by these formulae for different values of to become familiar 
with their differences. 

Columns, Diagrams, and Tables. The most useful diagram 
for the calculation of capacity of columns and of required areas 
under concentric loading is one which gives the allowable unit- 
stress according to the formula to be used. Such a diagram would 
be made by laying off vertical ordinates representing different 
values of radius of gyration, and horizontal ordinates representing 
length of column in feet. On this diagram curves could be 
plotted, corresponding to a number of formulae. 





STEEL CONSTRUCTION 


117 


Plare HI 


Cast Iron Ribbed Bases 


















































































































118 


STEEL CONSTRUCTION 


In practice this diagram would be used as follows ; Assume 
a certain section which the judgment of the designer indicates as 
approximately correct. Calculate the radii of gyration, and, this 


Plate IX. _ Column Schedule 


Story Heights. 

Cols. Nos. 

1. £.3.4.7 9.11 
12.13.17.18.2Q 
21.22.26. 

Cols. Nos 

5.6.8.IO.I4I5. 

16,19.23.24,25, 

272&S4 

Cols. Nos 

29.SO.SI.S2, 

SS.S5.36 


ROOf 

HU' 

1 

nth 

Web 10 xf 
4 l5.3ix3x&\. 
Area=10.35° 
Load=36 Ton5 

WebQxf 
4 ls. 31x31x 1 
Area = 16.00° 
Load=36Tons 

Web 10 xf 
4L5.3[x3x£. 
Area=10.35° 
Load =5 Hons. 

X 

'n 

10th 

-x- 

K 
- 1 

Y 

9th 

Web lOXi 
4L54x3xi ". 
Area=/4.93° 
Load=79Ton5 

Web IO"xi n 
4 l5.3x3x£ 
3p/5.dxf 
Area-30.19 ° 
Load=63Ton5 

Web IOx f 

4L5 4 X4xf .. 

Area-30.00° 

Load=t08Ton5. 

X 

V 

V 

&th 

t \ 

N 

i 

Y 

7th. 

Web 10 x£ 
4u54x3'xi" 
3pb. I0"x § . 
Area- 22.42° 
Load=U9Tons 

Web ip"xz\ 
4 l54x3x§" 
3pb. I0"xre" .. 
Area=33.67° 
Load=IOOToti5 

Web 10 x£ m 
4L5.4 x4 Xi" 
3pt5 10X3' : 
Area=3Q.75° 
Load=!63Ton5 

A 

IY 

Y 

6th 

• I 

5 

Y 

5th 

Web IOx f 
4L5.4 'x4x£ 
3pb/ox§ .. 
Area-37.50° 
Load=t60Ton5 

Web. 10 xf 
4LS 4'x4"x£ 
3pb lo'xf „ 
Area=30.00° 
Load = I361dns 

Web 10 xf 
4 ls4x4"x£ 
3pt5 HXf .. 
Area=3Q.44° 
Load=3ldTori5 

N 

' i 

$ 

Y 

4th. 

. K 

K 

'o 

v 

3rd 

Web 10 xf 
4L5.4 x4x£ 
3pl3. /Oxf . 
Area =54.69° 
Load=l99Tori5 

Web /Ox £ 
4L5.4”x4"x g 
3p/5. H"x J"., 
Area=37.07° 
Load=/73Tori5 

Web IOx £ 
4L5. 5x5 Vj" 
3pl5. //Xf" . 
Area 4744° 
Load=373Tm 

X 

$ 

-¥- 

3nd 

> 

Y - - 

/5f 

Web Ifx? 
4L5 4'x4xi 
3pb. IOx§ . 
Anea=5994° 
Load=339lai5 

Web 13 xf 
4l5. 4x4 xf 
3pb. l/xf 
Area=43.94° 
Load=3!OTon5. 

Web I3xf 
4L5. 5x5xf 
3pl5.IIXf .. 
Area-5746° 
Load=337Toti5. 

A 

T 

Y 

Basemenr 


Fig. 107 


having been done, the allowable fibre strain, for the least ratio 
of length and radius of gyration can be taken from the diagram. 




























STEEL CONSTRUCTION 


119 


If the area as determined by this allowable fibre strain varies 
materially from that of the assumed section, a new assumption 
must be made and the process repeated. 

Problem. Plot on cross section paper which is divided into 
spaces inch square, a column diagram as described above, and 
draw curves for each of the formulae given ; ordinates to provide 
for radius of gyration from 0 inches to 8 inches, and of length 
' in feet from 0 feet to 60 feet. The scale to be T \ in. — 1 ft., and 
T 2 <y in. z= 1 in. radius. 

Tables or diagrams are also made of the safe capacity of dif¬ 
ferent column sections for varying lengths, as, for instance, those 
given for Z-bar columns and for channel and plate columns. Sim¬ 
ilar data could be prepared for other types of column; but unless 
the designer were working under one column formula constantly, 
such tables, in order to be useful, would need to be made applica¬ 
ble to all formulae, and would, therefore, involve considerable time 
in their preparation. 

The column loads should be tabulated with the sections of 
columns as illustrated by Plate IX, Fig. 107. These loads are 
the reactions from the different beams framing into them. 

Practical Considerations. In general it is the practice to 
vary the section of column only at every other floor. The reason 
for this is that the saving in number of pieces to handle and 
to erect, and in splices, and the gain in time of delivery, more than 
offset the extra metal added in one story. 

In some cases, also, it is advisable to adopt a uniform dimen¬ 
sion column so as to avoid changes in length of beam from story 
to story that would be necessitated by even slight changes in size 
of column. In special cases many other practical points are likely 
to arise, which, by affecting rapidity of preparation of drawings, 
or of shop work, or of erection, may make it advisable to adopt 
certain forms, or may affect the theoretically economical section. 
The successful designer is the one who can foresee all these con¬ 
siderations and properly weigh their effect. 

Cast=Iron Columns. Where the .conditions are such as 
to require a rigid frame, and consequent stiffness in joints and 
connections, it is not advisable to use cast-iron columns, because 
connections to such columns must always be by means of bolts, 





120 


STEEL CONSTRUCTION 


which are apt to work loose and which never fit the holes perfectly. 
Furthermore, cast-iron columns are ill adapted to resist lateral 
deflection. Their use, therefore, should be confined to buildings 
of moderate height and in which the walls themselves furnish all 
necessary stiffness. 

In order to use the formulae for strength of cast-iron columns, 
given in Table 10 of Part I, the ends must be turned true. If 
this is not done not more than one-half their values should be 
used. 

Concrete and Steel Columns. Considerable attention has 
been given of late to the strength of steel and concrete columns. 
Some systems have already been proposed, in which columns com¬ 
posed of rods imbedded in concrete are used. Such construction 
has been used to some extent for chimneys, and in a few build¬ 
ings. It is also suggested that in certain classes of buildings, 
notably mills and manufactories, the steel members now quite 
commonly employed for columns could be encased in a solid and 
substantial envelope of concrete, and that this casing not only 
would have the advantage of fireproof protection, but, by the added 
stiffness afforded the columns, would enable higher fibre strains to 
be used in the design of the steel members, and would thus result 
in better and cheaper construction. 

PROBLEMS. 

1. Determine by use of the column diagram described in the 
problem above, the proper section of plate and four-angle column 
to carry a girder over the top, bringing to the column a load 
of 100 tons. Unsupported length of column 18 feet. Use Gor¬ 
don’s formula. 

2. In the above problem substitute for a plate and angle 
column a box column composed of channels and side plates, and 
determine proper section by use of Carnegie formula and American 
Bridge Company formula. 

8. Given a column built into a 16-inch brick pier and loaded 
with 125 tons. Required the proper section of plate and angle 
column, assuming column to be stiffened by wall in direction of 
wall. Length 16 feet. Use Gordon’s formula. 



STEEL CONSTRUCTION 


121 


4. Given a column loaded as shown by Fig. 114. Deter¬ 
mine proper section of plate and angle column, using Gordon’s 
formula. 





Fig U4 Fig. 115, 


5. Given the same column as above, but with the axis of 
column at right angles to previous position, as shown by Fig. 115. 
Determine required section of column using channels either latticed 
or with side plates. Use Gordon’s formula. 





























122 


STEEL CONSTRUCTION 


TRUSSES. 

For spans under 35 feet, a riveted or beam girder is ordinarily 
more economical than a truss, unless the conditions of loading are 
peculiar. 

Selection of Type. The type of truss selected depends gen¬ 
erally upon (1) span, (2) pitch of roof, (3) covering of roof, (4) 
available depth, (5)' load to be carried. 

All the above considerations affect jointly the choice of type; 
no single type would be used under certain lengths of span, for 
instance, with different combinations of the other conditions. A 
short span and flat roof might lead to a lattice truss, but if the 
roof had a steep pitch another type would be used. 

The covering of the roof affects the position and number of 
panel points, and therefore the type. If the planks rest directly 
on the top chord of trusses, then the panels can be arranged as 
may be most economical. If the roof is of corrugated iron, the 
size of sheets will limit the spacing of purlins, and, as these should 
come at the panel points, this will determine the number of panels. 

The position of a monitor or skylight would also largely deter¬ 
mine the number of panels. 

If the depth is limited, then certain types cannot economi¬ 
cally be used. If there is a ceiling or shafting to be carried, or 
any other conditions making a horizontal bottom chord essential, 
then this must be provided. 

In almost all cases, therefore, there are certain conditions that 
determine arbitrarily certain features of the truss, and these indi¬ 
rectly fix the type that should be used. 

On pages 109 and 110 are given types in general use, and a 
consideration of the points noted above will illustrate their appli¬ 
cation to these types. 

Bracing. An important feature in all trussed roofs is the 
bracing. Trusses cannot be economically designed without sup¬ 
porting at intervals the top chord against lateral deflection. As 
was noted in the case of beams, the allowable fibre stress must be 
reduced with the ratio of length to radius of gyration. 

This support is given by the plank if directly attached to the 
truss, or by purlins. Such purlins should be efficiently connected 
to the truss. If the conditions of framing are such that the regu- 



STEEL CONSTRUCTION 


123 


lar construction does not hold the truss, then special steel bracing 
must be used. In the case of very large roofs, special steel brac¬ 
ing should always be used, as there would not be sufficient stiff¬ 
ness in the connections of purlins to properly brace the trusses. 

Such bracing is generally of the kind known as X bracing^ 
alternate panels of adjacent trusses being connected by angles or 
rods. Not every bay is braced, but every other bay, or a less 
number, depending on conditions. 

Considerations Affecting Design of Trusses. Light trusses 
are subject to distortion in shipping, handling and erection. To 
guard against such distortion it is sometimes important, therefore, 
to provide more than the strength calculated for vertical loads 
when the truss is in position. 

In designing a roof, certain features that affect the weight of 
a truss can often readily be avoided. Some of these are indicated 
as follows: 

Long web members should be arranged so that the stress will be ten¬ 
sion, not compression. 

It is not economical to use a double system of web members, such as a 
lattice truss, except in the case of light loads and shallow depth. 

No web members should be provided that do uot take direct load or are 
not needed for support of the chords. 

Concentrated loads, such as purlins, or hangers, etc., should, if possi¬ 
ble, come at panel points, as otherwise the bending stress in the chords 
increases materially the weight of truss. 

.The roof plank resting directly on the top chord of truss increases the 
weight of truss, but the saving in purlins sometimes offsets this. 

The spacing of trusses should, if possible, be such as will develop the 
full strength of the members of the truss. In some cases the conditions are 
such that the lightest sections which it is practicable to use are not strained 
nearly to their capacity. 

Practical Considerations. Trusses are generally riveted up 
complete in shop and shipped whole, unless it is impracticable to 
do so. Not only is riveting in the field expensive, but the rivets 
are not so strong, being generally hand-driven instead of power- 
driven. 

In some cases it is not practicable to rivet the trusses com¬ 
plete, on account of their size. If they are to be shipped by rail¬ 
road, it is always necessary to be sure that they do not exceed the 
limits of clearance necessary along the route they have to traverse. 



124 


STEEL CONSTRUCTION 


These limits have to be obtained in each special case, as the clear¬ 
ances of bridges and heights of cars vary. This consideration 
sometimes makes it necessary to ship all the parts separately and 
to rivet in the field, or to make one or more splices of the truss as 
a whole. The weight of trusses, with regard to the rigging avail¬ 
able for handling and transporting them, has also to be considered. 

During the process of erection it should be remembered that 
in the design of the truss the lateral bracing of the completed 
structure is generally figured on, and until the structure is com¬ 
plete, ample temporary bracing should be provided. Many fail¬ 
ures of roofs are due to neglect of this precaution. 

Determination of Loads. The loads for which a roof truss 
should be figured are: the dead weight of all materials; an 
assumed snow load, varying with the latitude and slope of roof; a 
wind load, varying with the slope of roof; a ceiling load, if there 
is to be any; and such other special loads as may occur in particu¬ 
lar cases. 

Snow varies from 12 to 50 pounds per square foot of roof, 
according to the degree of moisture or ice in it. On a fiat roof an 
average allowance for snow is 30 lbs. per square foot of roof. A 
roof sloping at an angle of 60° to the horizontal would not gener¬ 
ally need to be figured for snow, unless there were snow guards to 
keep the snow from sliding off. 

The wind is assumed to blow horizontally, and the resulting 
horizontal pressure is generally taken at 40 lbs. per square foot. 
The normal pressqre with different slopes on this basis is indicated 
in the following table : 


TABLE XVIII. 

Roof Pressures. 

In pounds per square foot, for an assumed horizontal wind pressure of 40 lbs. per 
equare foot. 


Angle of Roof with Horizontal 

5° 

10° 

20° 

o 

CO 

© 

50° 

60° 

70° 

o 

00 

90° 

Pressure Normal to Surface of 
Roof 

5.0 

9.6 

18.0 

26.4 

33.2 

38.0 

40.0 

40.8 

40.4 

40.0 

Pressure on Horizontal Plane 

4.9 

9.6 

16.8 

22.8 

25.6 

24.4 

20.0 

14.0 

6.80 

0 

Pressure on Vertical Plane 

0.4 

1.6 

6.0 

13.2 

21.2 

29.2 

34.0 

38.4 

39.6 

40.0 

















STEEL CONSTRUCTION 


125 


In the calculation of the maximum strain, the combinations 
of dead load, snow load, and live load should be considered. It is 
not necessary, however, to consider the wind and snow acting on 
the same side at the same time as a wind giving the assumed pres¬ 
sure would blow all the snow off this side. Wind on one side and 



ZPanel Truss., 
F/g.f/6, 



3Panel. Truss. 
F/g-nZ 



4Panel Truss. 
Fy. H8. 


Flat Pitch Poor 7russ. 
F/g. I 19. 



Parallel Chord Roof Truss 
F/g. /20. 


snow on the other side, or snow on both sides, generally give the 
maximum live-load strains. 

The total dead and live loads should not be taken as less than 
60 lbs. per square foot, and, in general, the conditions render allow¬ 
ance for a greater total load necessary. 

The design of trusses will be taken up in the course on 
Theory and Design. 




















126 


STEEL CONSTRUCTION 


CONNECTIONS AND DETAILS OF FRAniNG. 

Figs. 121 to 126 show types of connections of beams to girders 
and columns. Connections to girders are nearly always of these 
standard forms, which are the Carnegie standards. In certain cases, 
individual shops have forms that vary slightly from these, but not to 
any great degree. It is essential to use the standard form wherever 
possible because these connection angles are always kept in stock, 
and the shop work of laying out and punching the material 'is 
thereby much simplified. Conditions of framing sometimes arise 
requiring special connections, but these should always be avoided 
if possible. In the smaller shops, an extra charge is generally 
made for coping beams so that where practicable, without increas¬ 
ing the cost of other portions of the work, it is better to frame 
beams far enough below girders to avoid this coping. The larger 
shops, however, are so equipped that this coping does not involve 
an extra operation, and a beam that must be cut to exact length, 
and has framing angles, can be coped without extra charge. 

Connections of beams to columns where they frame centrally 
with the columns are of the general type shown by Figs. 95 to 105. 
The exact size of angles varies somewhat with the column section, 
because the riveting in the framing angles must conform to the 
spacing required for punching the members of the column. If the 
beams frame into the column eccentrically, no standard forms can 
be followed, but each case must be treated individually. Plate 
and box girders draining into other girders are generally connected 
by angles riveted to the webs, because ordinarily the depths of the 
girders will not allow shelf angles underneath. Where such 
girders frame to columns, however, it is better to use shelf angles 
with stiffener angles, or shear angles as they are generally called, 
because this facilitates the erection by providing a seat upon which 
the girders can rest when swung into position, and also because 
side connections would cause bending stresses in the column, as 
noted on page 112. 

Column Caps, Bases and Splices. Where heavy girders or a 
number of beams come over the top of a column, the column 
section should be made up of such shapes and of such size that the 
metal of the column comes as nearly as possible under the metal 



STEEL CONSTRUCTION 


127 


STANDARD BEAM CONNECTIONS 




bin 


■fr 


7 


2.ls.6*4*Yb I° n 9 

k /eight- ZJ/bs. 

For -1 Beams and Channels. 

Fig. 121. 






K 


k 


ils 4xT*E I 1 3 "long 
Weight 36 lbs. 

For 16 


-& 


\ ZO~.~Beams 


1 


i 



r 

Tr! 

RXl 

n 

C 

Vi 

* c ! 

^ ^ 1 

] q 

9 NS 

V " 

_ 

Fig. 122. 

i— 



2z*6* 

“4-*-fg /enoths as 
be /on . 

^k-> 

-4 ; 



’ For J "/ Wasabove°2"long foriWQeams+Cfianek V/t. 7/bs. 
Z'As - • 5’ ' * 

e m • - 


2&* 

3" 


For 7 <3 ,9', to" 
Reams and Channels 


'-"1 



... j 

T7 

K j 

A 




bi. 


n 

r 1 

h . 

y 

vl 

1 ^ 

I /: 

9 ^ 

i) 

T V| 


P 


! ^ 

9 ^ 


Mi 

£22* 

- 





0-3"/9 

wr / 6'— /6 7 





Fig. 123. 




dlS -6 ~x4x,i-o-'/o'/0nff 
Weyhf J//bs 








~T~ 

nlf 

•0 

rl 


nit 

K> 

A 


For IS — Beams ana/ Channels 


Fig. 124. 


Fig. 125. 



For 24-'~ Beams- 


<b 0> 




































































































































































128 


STEEL CONSTRUCTION 


of the beams or girders. If the girder has stiffener angles over 
the bearing, as it generally does, shear angles should be put in the 
column directly underneath. The webs and stiffener angles of 


TOP PLATE OF CAP OF COLUMN PLAN SHOWING RELATION OF BEAMS 

OVER TOP OF COLUMN TO LINE WITH 
MEMBERS OF COLUMN 



SPECIAL CONNECTION-3 BEAM GIRDER OVER TOP OF COLUMN. 

Fig. 127. 

the girders or beams should not bear on an unsupported cap plate, 
but this cap plate should be well supported by shear plates or 
angles. The above is illustrated by Fig. 12T. 

Column splices are not ordinarily designed to carry the full 
load of the upper section through the splice to the lower section. 
Such design would result in splices of considerable length, which 







































































STEEL CONSTRUCTION 


129 


in some cases would be difficult to arrange and always expensive. 
I lie general practice is to have the top of the section below and the 
bottom of the section above the joint planed to a true surface so 
that there will be a perfect bearing between them. If this is done, 
the load is transmitted from section to section by direct compres¬ 
sion just as in the body of the column. However, the splice 



Fig. 128. 



TYPES or COLUMN JOINTS 

Fig. 129. 


should be designed to give, the column the full strength of the 
uncut section as regards stiffness against lateral deflection. As 
the splice is near the floor beam connections, where the column is 
braced laterally, this can generally be easily accomplished. Types 
of column splices are shown by Figs. 128 and 129. 

Fig. 130 illustrates a connection to column of a beam located 
eccentrically with regard to the column. 

Such connections require an extra number of rivets in addition 
to those required for the direct load in order to resist the tendency 
to rotation due to the eccentricity. 

Some of the special types of framing which occur are shown 
by Figs. 131 to 140. 

Where a beam comes below another beam, as shown in Figs. 
131 and 132, a connection such as shown can be used. If the 
load coming on the hanger is such as to require something stronger 
than a channel, a simpler connection will result by using two 


































130 


STEEL CONSTRUCTION 


channels spread far enough for the connection plate to be riveted 
between, as shown by Fig. 132, instead of a beam. 

A three-beam girder framed to another beam is shown in Fig. 
133. The inside beam can have angles on each side of the web. 
This beam must be placed before the outside beams in order to 



make this connection. Unless the three beams are spread a con¬ 
siderable distance apart, the outside beams can have an angle on 
only one side of the web ; this angle therefore should be a 6"X 6" 
angle in order to get the same number of field rivets as with two 
standard angles. 

Fig. 134 shows a beam dropped below the the top of a 24-inch* 
beam girder to which it is framed. With these large size girders 
it is often impossible to make a connection so that the beams will 
frame flush with the girder. 

Figs. 135 and 139 show changes in the position of standard 
framing angles on the sides of webs of beams of different sizes 
framing on opposite sides of the same girder. These changes are 
necessary in order to use the same holds for both connections and 
to keep the connections standard. 

















































STEEL CONSTRUCTION 


131 




# 







































































































































































182 


STEEL CONSTRUCTION 



Connections for lSend7-js. framing 
opposite ff each other 



Beams framing on same 
side of Carder 




Connections for 6'Beam framing 
opposite to w 'Beom, o 'Beam 

or a'Beam 

Fig. 139. 

TYPICAL SPECIAL 

conriECTions. 



cLlvation. 


Connection for beam 
Framing to Girder on shew 












































































































































STEEL CONSTRUCTION 


133 


Fig. 136 shows the connection of a beam framing partly 
below and above another beam where the lower flange has to be 
cut. In such cases the angles which are riveted to the web for a 
bearing should extend back on the web beyond the cut for a dis¬ 
tance sufficient to get as many rivets in as are required for carry¬ 
ing the end shear. Therefore in this connection there should be 
at least twice the number of rivets required to carry the end 
reaction. 

Figs. 137 and 138 show minimum spacings of beams in order 
that connections qiay not interfere. 

Fig. 140 shows a beam framing on a skew to another beam. 
If this bevel from the perpendicular is more than one inch per 
foot, bent plates should be used rather than angles. 

Eccentric connections differ in form with the special condi¬ 
tions of each case but they should be so arranged as to distribute 
the load, so far as possible, over the whole area of the column 
section and not entirely on one side. 

The foregoing remarks apply also to the design of cast-iron 
web bases, such as is shown by Figs. 112 and 113. The box of 
the base should have its metal made to conform in position to the 
metal of the column and the ribs and base plate should be made 
of sufficient thickness to form a base stiff enough to distribute 
the column load uniformly without failure. The tendency in 
such bases is to split along the line of the central box or across 
one corner, and the ribs serve to brace the lower plate and resist 
this tendency. The same tendency would exist in the case of a 
steel plate riveted to the base of the column and the various 
shear plates and angles used in such cases are for the purposes of 
stiffening the plate sufficiently to enable it to distribute the load 
without failure. The design of such steel and cast-iron bases 
will be taken up later. 

Roof Details. Some of the forms of framing met with in 
roofs are illustrated by Figs. 141 to 143. If the roof is framed 
entirely with beams for the purlins and rafters, more simple con¬ 
struction will result if the webs are all placed vertical rather than 
normal to the plane of the roof. The two forms of connections 
are illustrated by Figs. 144 and 145. Where the rafters or purlins 
run over the tops of trusses, however, they are frequently normal 



134 


STEEL CONSTRUCTION 


to the plane of the roof and in such cases the connections are 
generally simpler than where the members frame together. 



Relation to Other Work. It is generally necessary to 
exercise care in all special connections not to interfere with the 
architectural features, and to keep the connections within the limits 
fixed by such features. Full-size sections and details should 


























STEEL CONSTRUCTION 


135 


generally be worked out, which will determine the exact relation 
of all portions of the framing to adjacent construction. Such 
details should be followed in common by the structural draftsman 
and the draftsman laying out the stonework or interior finish or 
other adjacent work. 




Inspection. Steel and iron members are inspected in the 
mill, the shop, and on the job. As referred to in the section on 
specifications, the stock from which the material is rolled is 
systematically tested to determine whether or not it comes up to 
the requirement of the standard specifications. When it goes 
into the shop a different kind of inspection is required. First it is 
necessary to see that the drawings are accurately followed both as 
regards details and sizes of members and as regards measurements. 
The rivets and holes must be accurately spaced and the work 
properly assembled, for if carelessness in such details goes 
unnoted the different members will not go together when brought 
to the job and the whole piece may therefore have to be discarded. 
Secondly, the inspection must cover the quality of the work. 
This latter division applies almost exclusively to riveted work. 
Some of the important points to be noted are the following: 




































136 


STEEL CONSTRUCTION 


The members must be straight and free from twists and' bends. 
Punching must be sharp and true and holes must not be more 
than inch larger than the diameter of rivet. Holes must not 
be left with ragged edges after punching. Where necessary to 
get a clean-cut hole, or where required by the drawings, holes 
must be reamed after punching. 

Members when brought together to be riveted up must have 
the holes in the different pieces exactly opposite so as not to 
require drifting in order to bring them together. When driven, 
rivets must completely fill the holes, and must be of such length 
that, when the head is formed, the pieces will be brought together 
under pressure. Rivet heads must be concentric with the axis of 
the rivet. Column ends or other surfaces specified to be faced 
must be brought to a true surface exactly at right angles with 
the axis of the member. All portions of the material not accessi¬ 
ble after assembling must be painted before being assembled. 

In inspecting cast iron, tests must be made to determine 
whether or not it comes up to the requirements of the specifica¬ 
tions as regards quality. Inspection must also be made to see if 
the material is free from flaws such as blow holes, pockets of 
sand and unequal distribution of metal. Where the thickness 
cannot be measured readily as in the case of columns, small holes 
are bored to determine this. Where columns are cast in a hori¬ 
zontal position, as they generally are, the tendency is for the core 
to sag in the center, and therefore it is better to make this test 
near the center. A sharp blow of a hammer will often indicate 
unequal distribution of metal. A clear metallic ring indicates a 
thin shell and a dull heavy sound a thickness of the shell. If 
the edges are struck with a hammer and pieces fly off under the 
blow this indicates a brittle texture; a good quality iron should 
show only a slight indentation. Cast iron should be inspected 
also for straightness, accurateness of facing of bearing surfaces, 
and agreement with details. It is better to inspect cast iron 
before it is painted in order to the more easily discover flaws. 

Relation of Engineer to Architect. An essential feature to 
be observed in all successful designing and detailing by the 
engineer, is co-operation with the work of the architect. This 
may seem, to the student, at the outset, as a very simple point and 





STEEL CONSTRUCTION 


137 


one which will need little special attention. Yet the power to 
fully and quickly grasp the breadth of the architect’s design, and 
its smallest details as well, and to make the structural design to 
fully harmonize with his work, will come only by persistent effort. 

In some buildings, the work of the engineer, because of the 
character and purpose of the building, would determine conditions 
and features to which the architect must conform, but in general 
the reverse is true. For this reason the burden of harmonizing 
his work is generally put upon the engineer. 

He must see what has been established by the architect and 
how much he must vary the natural course of his design to con¬ 
form to these conditions. He must often study long, over what at 
first seems scarcely possible to accomplish without clashing with 
the architect’s scheme. In the working out of such details and 
problems, he will need all his originality. 

Interpretation of Drawings and Specifications. In prepar¬ 
ing the working drawings, the draftsman generally has to do with 
the design of another. To this extent, therefore, he is not respon¬ 
sible for the harmony of the design with the work of other lines. 
He is, however, responsible, if such a conflict of design escapes 
him, for it will be a sure indication that he has not looked at his 
problem from all sides, and in the light of later and more definite 
information which was, perhaps, lacking when the design was first 
made. 

In working up the shop details, the draftsman must start with 
the question constantly in his mind, “ How do I know?” He must 
not fix a measurement, nor establish the position and relation to 
other parts of a single piece, unless he finds concrete authority in 
the shape of plans, specifications, or written directions for so 
doing. Further than this, he must determine that all the infor¬ 
mation so given is in agreement, for he will be held responsible for 
failure to discover such disagreements. 

There is a great tendency among those young in experience 
to be guided by what appears to be indicated. Drawings are not 
always made to exact scale and the structural draftsman should 
never establish anything by scaling without explicit directions for 
so doing, and should then make a written record of what has thus 
been established. 



138 


STEEL CONSTRUCTION 


One of the most important instructions which can be given a 
draftsman, is never to jump at conclusions. Have direct authority 
for all that is done and be sure your authority is not contradicted 
in some other place. Oral instructions should be at once written 
down, as when once followed, they may become a necessary factor 
in other work. If information is lacking or there is a conflict, 
however small, in any of the information which is the basis and 
authority for your wo.rk, refer it at once to some one above you 
who can carry it to the one in authority. 

Shop Practice and Use of Detail Shop Drawings. When 
the shop details are prepared they go first, if the stock list has not 
previously been made, to the stock department, and a detailed bill 
of material required in fabrication is made. This is used either 
to make up the rolling lists or the lists of stock to be taken from 
the yard. The next step is the making of templates. These are 
patterns in wood of the exact size and shape of each piece, with the 
holes located, so that they can be used to mark out the piece itself. 
Formerly, the template maker did a good deal of the work now 
done by the draftsman, but in most shops the policy at present is 
to do as much in the engineering department as possible and to 
leave nothing to be worked out in the template room or shop. 

The templates are sent to the shop and the material goes from 
one machine to another, being cut to length, coped, mitred, bevelled, 
sheared and punched as required. 

When all the pieces are ready they go to the Assembly Shop 
and are then riveted up to form the finished piece as required by 
the drawings. Each piece has its letter or mark to designate it in 
its passage from the template room to the Assembly Shop; and 
when the whole piece is assembled it has a mark conforming to 
what is given on the setting or erection drawing, so that, when 
received at the job, the erectors will know where it goes. 

The final work is the painting, marking, invoicing and weigh¬ 
ing and then the shipment. 

Relation of Shop Drawings. The basis of all shop details is 
the setting plan, or erection plan. This shows the framing of the 
floors and roof, generally a separate plan being required for each 
floor and one for the roof. This framing plan has all the necessary 
dimensions to fix the location of each piece, the numbers or marks 



STEEL CONSTRUCTION 


139 


designating each piece, the size of piece, and such necessary sec¬ 
tions and notes as are required to fix the relation of the different 
members and to cover any special features. 

Each piece must be detailed fully, with cuts, punchings, and 
framings clearly shown. In general, a standard size beam sheet, col¬ 
umn sheet, and girder sheet are used; truss sheets are made to 
standard sizes as far as possible hut on account of the different 
types and sizes of trusses, more variation is necessary. 

Only one tier of beams is put on a single sheet even if of 
identical detail; also but one section of columns is covered by the 
same details. If the drawings are going into the mill, a further 
separation of the different sizes and shapes is necessary so that 
materials which have to be made in different mills shall not be 
detailed on the same sheet. 

Standard Forms. The specific types of sheets and details 
will be taken up later. 

There are standard forms of connections which cover all but 
special cases and which are used wherever practicable. 

Figs. 146 to 148 show framed, coped, and bevelled beams. 

There are certain conventional sizes and standards which 
should be known to those who have anything to do with working 
drawings. 

A setting plan can be so jumbled and confused by careless 
arrangement of data, and by poor execution that it will take 
longer for the man on the job or in the shop to determine its inten¬ 
tion than to work out independently what he wants to know. 
The draftsman should aim to put himself in the place of the shop 
foreman or erector, who, when he takes up the work, must rely 
entirely on this plan for all the information. He must aim to 
give all the necessary information and give it so plainly that it can 
be quickly seen and cannot be misinterpreted. 

Wall lines are shown by red lines in order not to be confused 
with the beam lines. The walls shown are those upon which the 
beams rest. For instance, the setting plan of the first floor beams 
will have the basement walls shown and the second floor plan will 
have the first story walls shown. Columns are represented by a 
single line indicating the members composing the columns ; this 
is illustrated by the columns shown in Plate I. It is important to 




140 


STEEL CONSTRUCTION 



BEAM FRAMED BELOW TOP OF GIRDER 



BEAM FRAMED FLUSH WITH TOP 
OF GIRDER AND COPED TO IT 































































































STEEL CONSTRUCTION 


141 


indicate clearly the composing elements so as to show which way 
the web of the column sets. 

Beams and girders are indicated by single lines corresponding 
to the center lines of webs of beams and backs of channels. All 
lines indicating the steel members should be heavy black lines. 
Beams framing into a girder or column are indicated by stopping 
the line of this beam a little short of the line of the girder or of 
the column. Where a beam runs over another, the lines indicat¬ 
ing them cross or, if there is likely to be a question, a note is put 
on to this effect. 

Lintel beams are shown on the framing plan of the floor just 
above the opening; for instance, lintels over the first story open¬ 
ings would be shown on the second floor plan. 

Measurement lines are put on in red, and should locate all 
bearing walls and all columns and each piece of steel. Beams are 
located by their center lines ; measurements to a channel should 
go to the back. Channels placed against a masonry wall are 
generally put with their backs one-half inch away from the 
wall. 

Tie rods are not located by dimensions on the plans except 
in special cases where a rod must come in a definite position to 
escape some other member. 

The size of beams are marked along the line indicating the 
beam. In cases where there are a number of beams in the same 
bay of the same size, it is better to use the symbol “ do ” or write 
the size once and indicate on the drawing. 

Each piece is given a number. The pieces maybe numbered 
consecutively or it is the practice in some cases to give the same 
number to all beams which are identical as regards size and detail. 
In all cases, the number or letter which serves to identify the 
piece should be put on conspicuously as this is what should be 
easily seen when using the plan. 

The size of bearing plates should be specified either at the 
wall end of the beam or by a general note, giving the sizes of 
plates for different sizes of beams. 

The general notes should also give the letter designating the 
floor as “ A ” for first floor, “ B ” for second floor, etc. 

The grade of underside of all beams should be given in the 



142 


STEEL CONSTRUCTION 


body of the plan or by general notes and the relations of tops 
or bottoms of all beams to each other and to the finished floor 
line. 

Sections should be made showing the framing over windows 
and of all special connections, and the relation of the different 
members to each other. In short, the setting plan must be a com¬ 
plete and final expression of all the data which has been gleaned 
from the general plans and specifications, and must be a guide to 
the shop man and the man at the job in fabricating, shipping, and 
putting the frames together. 

Beams are generally marked thus : “A-No.125,” or “ D-No. 56 
the lowest tier of beams being given the first letter in the alphabet, 
and so on in order, or First Floor No. 125, Fourth Floor No. 56, 
and so on. 

Columns are generally marked “ 1st Section No. 10 ” or “ 3rd 
Section No. 5.” Columns are sometimes made in only one story 
lengths but more often in two. They are sometimes marked thus : 
Col. No. 10 (0-2) or Col. No. 5 (4-6). 

The joint in a line of columns should come just above the 
connection of the floor beams. 

Hill or Shop Invoices. These are detailed schedules sent 
out by the mill when shipments are made. They give the desig¬ 
nation of the piece with its weight. and all connections and the 
mill marks, also the marks identifying it on the setting plan. 
These invoices are valuable as showing just what material has 
been shipped and in what car and on what date, and also serve to 
fix the weight when this is made the basis of payment. A form 
of invoice used by the mills of the Carnegie Steel Company is 
given by Fig. 149. 

Estimating. In making an estimate of the cost of steel work, 
the basis is always the weight of steel of different kinds. This is 
determined by taking from the general or framing plans a detailed 
schedule of each piece of steel. As framing plans are always 
shown to a small scale and include only the general features of 
the framing, this work requires special training before it can be 
done accurately and in the most efficient manner. 

In taking off quantities, the estimator generally scales the 
lengths as these are not usually given by figures. A test of 



STEEL CONSTRUCTION 


143 


measurements given by.the general plans should be made when 
possible, to see how nearly to scale the drawings are made. A 
close estimate should not vary much more than 2.t% or 3 % from 
the . actual weight, so it will be seen that considerable care is 


necessary. 


CARNEGIE STEEL COMPANY. 

HOMESTEAD STEEL WORKS. 

STATEMENT Of DCTAIL-3 Of CONSIGNMENT MAO£__ -i90i^i Bill Number J1S437_ 

_ --- 5h „ t MuMBe * jsfs 

&e 7 £T$ > 




To _._ in car 

_L_ 


0»De* nt 

PRICE f MILL 

IKv 


Pieces 



ien 

rerr 

OTM 

m3 

total lpm 

r«T 

51^ 

Weight 

DESCRIPTION 

mark 


9A 

ijfyt 


v 









■ 





A 

'ttr/f 

/ 


' p 

'f/yZj. 


4 

a 

fist? 









FAz 

t 

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/to- 

cr 



/ 

4 

/z&\ 

7 





9JL 


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J70 



4 

6x4 

<m 

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/S 





4k 


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Fig. 149. 


Individual estimators have different methods of separating 
the different classes of material. 

The following are the general divisions of material: 

I. Beams and channels 15 inches and under. 

(a) . Plain beams and channels. 

( b ) . Beams and channels, punched two or more sizes of 
holes in web. 

( d ) . Beams and channels, punched in web and flanges. 

(e) . Framed beams and channels. 

(/.) Framed and coped beams and channels. 

II, Beams and channels 18 inches and above. 

The above divisions apply also to these sizes of beams and 
channels. 

There is an extra charge for all beams and channels over 15 
inches deep, therefore these sizes must be separated. 

Further, all the other shapes must be kept separated from 
beams and classified by themselves in a manner similar to the 














































144 


STEEL CONSTRUCTION 


division of beams. For instance, the members composing the 
columns as plates, channels, angles, zee bars, etc., are each kept 
by themselves. 

All connections of beams to girders and columns are charged 
at a different price from ordinary angles or plates, and must there¬ 
fore be figured separately. In a like manner tie rods, anchors, 
beam plates, column bases, separators and bolts all are classified 
separately. 

It is evident that these different divisions cannot be made at 
the time the schedule is taken from the plans, and it is customary 
to take off the material in order as it appears on the plans, and by 
some system of marking designate the class to which the piece 
belongs. The separation is then-made when the weights are cal¬ 
culated and the quantities are being totaled. 

It is also evident that such things as separators, framing, 
connections, splices, and other details cannot be taken directly 
from the plans, .but must be calculated largely by the judgment of 
the estimator. He must be able to see just what character of 
connection is required in order to classify correctly his material 
as he takes it off. 

Effect of Changes. Changes in details must sometimes be 
made from causes beyond the control of the draftsman. A 
change in the location of certain members, or the general arrange¬ 
ment at a certain point, may make it necessary to revise drawings 
already made and perhaps sent to the shop. In such cases, the 
drawing generally bears the same number and is marked revised. 
In case additional sheets must be prepared, of course new num¬ 
bers are given to them. In sending out a revised drawing, 
instructions should be sent to have the original sheets returned in 
order that they may all be destroyed and thus remove all liability 
of the material being made up by the old drawings. Revising 
details already completed and checked are fruitful sources of 
errors. Unless the greatest care is exercised, the changes made 
will affect the relations to some other members and the details of 
some other portions of the work not at first apparent. The drafts¬ 
man should have this point always in mind and review all possible 
connections to other work when revising any details. 

Use of Details in the Work. The detail drawings must 



STEEL CONSTRUCTION 


145 


frequently be used in determining features of other work and in 
laying out such work, and for this purpose the detail drawings 
should contain information enough to establish the relation of 
the steel to such working lines as finished floor levels, datum 
line, ashlar line, party line, and such other lines used in the 
general drawings to establish the relations of the different parts 
of the work. 

FOUNDATIONS. 

There are three general types of foundations. 

(1) Spread foundations. 

(2) Foundations to bed rock by piers or caissons. 

(3) Pile foundations. 

The form of foundation used depends largely on the charac¬ 
ter of underlying soil, and the 
amount and arrangement of the 
loads and the depths which can 
be allowed for foundation. 

Spread Foundations. This 
general division covers all forms 
of construction in which the 
foundations are spread out suffi¬ 
ciently, either by offsets of 
masonry or by steel beam grill¬ 
age, to distribute the load with¬ 
out exceeding the safe-bearing 
capacity of the soil. Fig. 150 
shows a masonry footing and Fig. 

151 a grillage footing. Bearing 
capacity of soils vary consider¬ 
ably and there are no ^ rigid 
limits fixing the allowable bear¬ 
ing values of different kinds of 
soil. Table XIX represents -block stone footing under column 

i i i • Fig. 150. 

good general practice. 

In some localities, notably Chicago, footings, if they are to 
be spread, require the use of beams because of the relatively thin 
bearing stratum, the low allowable bearing value, and the magni- 



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i 



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-! i 











































146 


STEEL CONSTRUCTION 


tude of the loads to be supported. To offset by successive layers 
of masonry would require too great a depth for the thin layer of 
hard clay; it thus necessitates the use of grillage beams. In 
other places either masonry offsets or grillage could be used. 



Course 3- /£ 30 *1^ 
/oner Course /o- S>~- /£* 



In Boston the usual soil encountered is a stiff blue or yellow 
clay, 15 feet or more thick and underlaid with a boulder clay of 
varying depth, but generally of from 15 to T5 feet. Under these 
conditions footings for isolated columns are very commonly made 
by offsetting the masonry until the required area is gained. In 











































































STEEL CONSTRUCTION 


147 


some cases the water level and a combination of footings may 
make it desirable to spread by means of beams. 

Caisson Foundations. In a yielding soil, or where the area 
available for spread footings is not sufficient, or where these foot¬ 
ings would be excessive in size, foundations are often carried to 
bed rock. 

The most common method is by the use of compressed air. 
Generally steel caissons, of the size of the pier, are used. These 
caissons have their edges extending below an air-tight floor, thus 
forming what is called the working chamber. Compressed air is 
forced into this chamber which keeps out water and soft material 
and enables workmen to excavate. The workmen gain access 
through air-tight shafts with double sets of doors forming an air¬ 
lock between the pressure below and above; they of course work 
under the pressure of the compressed air. The material exca¬ 
vated is hoisted up through shafts and the caisson is sunk by 
building up the masonry foundation in the caisson at the same 
time the excavation is going on and this weight sinks it down. 
When the caisson has reached the grade at which it is to rest, the 
working chamber is filled with concrete making a solid founda¬ 
tion. 

Pile Foundations. Piles support their load both because of 
the friction between their surface and the surrounding soil and 
because of resting on solid stratum at the bottom. In some cases 
probably the greatest support is from the friction on the surface 
of the piles. They should be driven into a solid stratum far 
enough to resist any tendency to side deflection. In some 
instances, notably in old wharf construction, the piles have been 
driven through a soft mud perhaps fifteen or twenty feet, and 
only a few feet into the hard clay below. In such cases the piles 
have deflected under heavy loads, and have assumed an inclined 
position, their tops having moved laterally ten or twelve feet. 
This of course causes failure. 

Piles should be driven with care so as to be kept in line, and 
the blows should not be so heavy as to cause brooming either of 
the head or point. A number of rules are given for driving piles 
and for determining the load they will support. Two rules in 
common use are the following: 



148 


STEEL CONSTRUCTION 


Baker 


P —100 [y/ W h.+ (50 dy —50 d] 


W = weight of ram in tons 
w = height of fall in feet 
d — penetration at last blow in feet 
p — pressure in tons to just move pile. 


The last blow must be struck on sound wood. 


Trautwine 


46 W ^h 
P - 1 +12 d 

In determining this last penetration it should be observed 
that the pile must be driven continuously, as, if allowed to stand 
some time between blows the soil becomes settled around the pile 
and the friction thus makes the penetration much less. 

Some authorities advocate driving piles with the bark on and 
some with it off. If the bark is on, the piles should be cut in the 
fall as otherwise the sap between the bark and wood will ulti¬ 
mately cause the two to separate and the pile to slip within its 
bark. 

The building laws of some cities require the piles to be 
camped directly with granite levelers; most authorities, however, 
prefer a thick bed of concrete encasing the heads of the piles and 
capping them at the same time. 

The factor of safety should be from 2 to 12, varying with the 
accuracy of the knowledge of the loads to be carried and with 
the closeness with which the formulse used fits the conditions of 
the special case. Fig. 152 shows a footing supported by piles. 

Fundamental Principles. The essential points in the 
design of foundations is not to overload the soil so as to cause 
excessive settlement, and to so arrange and distribute the loads as 
to cause the settlement to be uniform. Some settlement is practi¬ 
cally sure to occur in almost all cases, but unequal c°ttlement 
causes strains in the structure and cracks in the masonry. 

If the supporting power of the soil is nearly uniform ove? 





STEEL CONSTRUCTION 


149 


the whole area of the building, the first problem is to determine 
the amount of load on each footing. This is not as simple as 
would at first appear. Not only is it uncertain just how much 
live load will be carried, but also what proportion of the whole 
building will be loaded with this live load. 


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Furthermore the dead load carried by the columns support¬ 
ing the walls forms a much larger 
proportion of the total load on 
these columns than does the dead 
load carried by the interior columns. 

The different proportion of loading 
on the columns must, therefore, be 
brought to a common basis by 
some assumption. In the case of 
office buildings, the actual live 
load which reaches the founda¬ 
tions is probably a small proportion 
of the total live load calculated 
over the whole area of all the 
floors. Moreover, the building has 
considerable time to settle from its 
dead load before any live load 
comes upon it. In order, therefore, 
to harmonize the settlement be¬ 
tween wall and interior columns it 
is better to use as a basis the dead 
loads and a certain percentage of 
the live loads—say 25 per cent. 

A table should be made of the dead load and 25 per cent of the 
live load of each column footing. The areas should then be made 
such that these loads on the soil would be the same per square foot 
in each case. Care must be exercised that in so doing, the total 
load of dead and live, or if the building laws under which the 
work is done permit of a reduction in live load, that this percent¬ 
age of live and dead does not bring the load per square foot above 
the specified amount. In general, this will not be the case if the 
column footing, in which the proportion of dead plus 25 per cent 
live to the total load is the least, is first proportioned for total load 


CONCRETE AND PILE FOOTING UNDER COLUMN 

Fig. 152. 

















































150 


STEEL CONSTRUCTION 


and the others then made proportional to it. The following 
example will illustrate this point. 

Problem. Suppose columns as follows : 

No. 1 Dead+25% live=407,000. Total load=629,000 

No. 2 Dead+25% live= 190,000. Total load=245,000 

No. 3 Dead+25% live—275,000. Total load=465,000 

Maximum allowable bearing on soil from total load to be 
5,000 pounds per square foot. 

In No. 1 the dead+25% live.is 64.5% of tlie total load on this column. 

In No. 2 the dead+25% live is 80 % of the total load on this column. 

In No. 3 the dead+25% live is 59.2% of the total load on this column. 

If then, we take column No. 3 as the basis we have the 
required area equal to 465,000 divided by 5,000 or 93 square 
feet. This gives 2,960 pounds per square foot from the dead -|- 
25% live load. 

For No. 1 in order to have the pressure from the dead -f- 25% 
live the same as in No. 3 we shall require 407,000 divided by 
2,960 or 137.5 square feet. This area gives 4,560 pounds per 
square foot pressure from the total load. 

In column No. 2 *we have 196,000 divided by 2,960 or 66 
square feet required, and the pressure from the total load is 3,700 
pounds per square foot. 

A further provision which must be made is to bring the 
center of gravity of the resisting area, or loaded area, coincident 
with the axis of the load. The same principle of a strut eccentric¬ 
ally loaded applies to a footing in which eccentricity of loading 
exists. In such a case equal distribution on the soil is impossible 
as the side on which eccentricity exists will always be loaded the 
most. Furthermore, a bending moment, as in a strut similarly 
loaded, will occur in the foundations, and even a slight eccentric¬ 
ity, if the load is considerable, will cause heavy strains in the 
footing. This latter point is sometimes difficult to accomplish 
because of the restricted area available for the footings. In some 
cases the loading and bearing capacity make it necessary to com¬ 
bine the footings of several columns, or the necessity of combin¬ 
ing the foundations under an old wall with new footings, or 



STEEL CONSTRUCTION 


151 


of providing for a future wall or column on the same foot¬ 
ing, or of keeping the footing for a column in a party wall 
entirely within the party line,— any or all of these conditions may 
make it impossible to fulfil exactly the conditions previously men¬ 
tioned. Departure from these principles should be as slight as 
possible, and when necessary direct provision should be made for 
the additional strains consequent thereon. 

The necessity of keeping footings inside of party lines, and 
the desire to make the axis of load conform to the center of grav¬ 
ity of area, sometimes results in the use of cantilever construction. 
These cantilevers are in some cases laid directly over the beams 
forming the grillage in the footing. This construction makes the 
actual point of application of the loads uncertain as any deflection 
would tend to throw the load on the outer beams. A better con¬ 
struction is the use of a shoe with a pin bearing. 

Improvement of Bearing Power. The supporting power of 
all soils is improved by compacting, by mixing sand or gravel or 
by driving piles which prevent the spreading of the soil as well as 
compacting it. Drainage of a wet soil also greatly improves its 
bearing power. 

The following table taken from Baker’s “ Treatise on Masonry 
Construction,” gives values for general use in determining the 
bearing power of soils : 


TABLE XIX. 


Safe Bearing Power 
Tons per Sq. Foot. 

Clay in thick beds, always dry.4 to 6 

Clay in thick beds, moderately dry.2 to 4 

Clay soft.1 to 2 

Gravel and Coarse Sand, well cemented . ..8 to 10 

Sand compact and well cemented.4 to 6 

Sand clean and dry... . 2 to 4 

Quicksand, alluvial soils, etc.^ to 1 


The bearing power of clay depends largely upon the degree 
of moisture. 

Foundations on clay, containing much water, and undrained, 
are liable to settlements from the escape of the water either by 
adjacent excavations, or by the squeezing out of the water. 










152 


STEEL CONSTRUCTION 


Moist clay in inclined strata is liable to slide when loaded. 
Clay mixed with sand or gravel will bear more load than pure 
clay. Sand will bear more load than ordinary clay, and when in 
beds of sufficient thickness and extent to prevent running, will 
bear heavy loads with little.settlement. Sand sufficiently fluid to 
run, as quicksand, cannot be easily employed to carry foundations. 

Grillage Foundations. The simple grillage foundation is 
illustrated by Eig. 151. The method of calculating the beams 



Fig. 



DIAGRAM or DISTRIBUTION OF COLUMN 
LOAD OH GRILLAGE FOOTIMG. 


153. 


composing the grillage involves assumptions as to the conditions 
of distribution of loading and stresses. One method is given in 
Cambria, Page 263. This method involves the assumption that 
the beams can deflect from the line of axis of column. Such a 
condition, however, would lead to the cast-iron base bearing at its 
outer edges only; this would involve strains for which these 
bases are rarely designed. Another assumption and one more in 
harmony, with the assumption of the ordinary beam theory, is that 
the beams of the upper tier are fixed for the portion under the 
column base. Under this assumption the load is distributed uni- 
































































STEEL CONSTRUCTION 


153 


formly by the upper tier and the stress in the free portion is 
calculated by the formula for a beam fixed at one end and free at 
the other. 

Referring to Fig. 153 ; suppose the column load is P, and 
by the principles already given the extreme dimensions of footing 
are L and L' in feet. The length of the beams in the two tiers 
can be taken as L and L r also. Then if b and V are the dimen¬ 
sions in feet of the column base, and the beams in the upper tier 
are placed the same width out to out of flanges as the column 


base, I- = projection of the upper tier, and — 


■b r 


— projection 


of the lower tier. The load per square foot on the upper tier is 

The moment in inch pounds, 


p p 

———, and on the lower tier is __ 

b' L LL 


therefore, is M = ^ X 


V P. (L-ft)a 


X 12 


_ a 


X jy (L — b~) 2 for the upper tier 


and M' —\X jy[r x —%—" 1 


= | Xyr(L'— b ') 2 for the lower tier. 


These formulas give the total moment borne by all the beams 
in the tier. The number of beams is generally determined by the 
dimensions of the footing, the beams of the upper tier being 
placed with their flanges generally not much more than 6 inches 
apart in the clear, and those of the lower tier from 6 inches to 12 
inches. The number of beams being determined, the moment 
each bears is obtained by dividing the total moment by the num¬ 
ber of beams; and by‘dividing this individual moment by the 
allowable fibre stress the required moment of resistance and 
hence the size of beams is obtained. Since the concrete and steel 
act together, a higher fibre strain can be safely allowed ; this 
should in general be not more than 20,000 pounds per square inch, 
however. 

Some trial and reproportioning of dimensions may sometimes 
be necessary to keep within the limits of depth and number of 










154 


STEEL CONSTRUCTION 


beams desired. Grillage beams in foundations should have the 
concrete thoroughly tamped around them, and it is preferable 
that the steel should be coated with neat cement instead of a coat- 
of paint. 



Diagram °jT Grillage Footing. 
Fig. 154. 


The following problem will illustrate the method of proce¬ 
dure in the case of combined footings. 

Suppose two columns loaded and spaced as shown by Fig. 
154, and let the allowable bearing on soil be 5,000 pounds per 
square foot. Let the dimensions of the footing be 20'— O" X 11 / 
— O"=r220 square feet. The determination of the size of base is 
largely a matter of judgment and depends upon the amount of 
load and the degree of spreading necessary to keep the size of 
grillage beams, or masonry offsets, within the limits which are 
economical. Suppose in this case the base is 3'—6" X 3'—6." The 

, , , , . , , 1 , 100,000 

load per square toot in the upper tier is therefore-oT.— k-t~ = 

X 3.o 

15,714 pounds. The moment on this tier will be a maximum 
either at one of the columns or at some point between them. The 

600,000X11 


center of gravity of load 


is 


1,100,000 


■ = 6, or 6 feet from the 


lighter load. This fixes the projection of the footing beyond the 
loads as 4 feet from the light load and 5 feet from the heavy load. 
The beams between the column loads are in the condition of a 
beam fixed at the ends and loaded with a uniformly distributed 
load. The moment may therefore be taken as approximately | of 
































STEEL CONSTRUCTION 


155 


that for a beam simply supported. The moment between the 
columns will be a maximum where the shear is zero. To deter¬ 
mine this start from one end, say the left-hand end, and deter¬ 
mine the distance to the point of no shear by dividing the 

600,000 


concentrated load by the load per linear foot; 


z=10.9. 


55,000 

If the load is assumed uniformly distributed over the upper tier 
the greatest moment outside of the column load will be at the end 
having the greatest free length. The maximum moment there¬ 
fore in this case will be at the edge of the base plate of the column 
at the left-hand end or 10.9 feet from this end. Call these 
moments M and M' respectively. 

M=|X 55,000 x 3.25 X 3-25 X 12 
= 3,487,000 inch pounds 

and M' = | X [55,000 X 10.9 X 5.45 — 600,000 X 5.9] X 12 
= 2,181,800 inch pounds. 

If the allowable fibre strain is taken at 18,000 pounds per 


M87,000 

"187000" 


square inch, the required moment of resistance = 

194. 

The offsets in masonry footings can be determined by the 
formula for a beam fixed at one end and loaded uniformly. A 
general practice and one in fairly close accord with the results of 
the above formula is to draw lines at 60 degrees with the horizon¬ 
tal from the edges of the column bases and where these cross the 
joint lines (the thickness of the courses having been assumed) 
will be the vertical face of the course. When the structure is of 
such a character that wind load affects the foundations, this 
must be considered in addition to the other live loads. Such 
cases would be narrow and very high buildings, chimneys, monu¬ 
ments, etc. 

While the concrete and imbedded steel beams in a footing 
are undoubtedly much stronger than the simple beams, it is not 
customary to figure the beams in such cases by the theory apply¬ 
ing to steel imbedded simply in the tension side of concrete. Foot¬ 
ings of this character are employed sometimes and their design 
will be taken up later. 




156 


STEEL CONSTRUCTION 


Cantilever Foundations. The case of cantilever construction 
supporting a party wall is illustrated in Fig. 155. Let P be the 
wall column load, a the distance in feet from wall column to the 
pin bearing forming the fulcrum, and b the distance in feet from 



fulcrum to column at opposite end of cantilever. Then the load 
on fulcrum is # The distance a should be taken so that 


the fulcrum can be at the center of the footing and still keep 
within the party lines. Sometimes this cannot be done, and then 
the footing has to be designed to take account of this eccentricity 
of bearing. The cantilever is designed by determining the maxi¬ 
mum moment and shear. The maximum moment in the above 
cnse is at the fulcrum and is P a in foot pounds. In case the 
girder is a riveted girder, as is often the case, other features must 
be considered in its design, as will be explained later. 

In case the cantilever is in the floor, as it sometimes is, as 
shown by Fig. 156, and in addition to the wall column, carries a 
floor load, then the position of maximum moment must be deter- 
































STEEL CONSTRUCTION 


157 


mined in a manner similar to that explained for combined footings. 
The connection of the cantilever at the interior column must be 
designed to resist this upward tendency and in case the reaction 
from the dead-wall load is greater than the dead load carried by 
this column the cantilever arm should be extended to the next 
column so as to decrease this reaction ; or the column must be an¬ 
chored and all connections designed to resist this upward reaction. 



Fig. 156 shows also a steel concrete retaining wall to hold up 
the earth under an adjoining building which foots some dis¬ 
tance above the new foundations. 

Fig. 157 illustrates the case of a party wall foundation 
designed to carry a future wall column for the adjoining building 
and the column of the present building. The eccentricity of 
bearing is shown in this case, and this and the necessity of spread¬ 
ing in the direction of the wall rather than across it are the 
important features. 















































































158 . 


STEEL CONSTRUCTION 




PLAN OF FOOTINGS AT CORNER 
UNDER CORNER COLUMN AND OLD WALL. 

Fig. 157. 






















































































STEEL CONSTRUCTION 


159 


The matter of design of foundations is one always requiring 
accurate knowledge of the special conditions incident to the prob¬ 
lem and the nature of the soil, and is largely influenced by prac¬ 
tical considerations and the judgment of the designer. It is not 
safe to lay down any fixed values to be followed in all cases. 
Foundations in soil which are at all questionable, should never be 
designed except by an expert, who is capable of judging the extent 
to which the ordinary methods of procedure must be modified. 

Retaining Walls are walls built to resist the thrust of earth 
pressure. These walls may also be bearing walls for loads above. 
The pressure of earth tends to cause failure of the wall in the 
following ways: 

(1) . To slide on its base. 

(2) . To slide on some horizontal joint. 

(3) . To overturn bodily. 

(4) . To fail by buckling. 

To resist the tendency to slide on its base, the dead weight 
of the wall, or of the wall and the load it carries, must be sufficient 
to resist the horizontal pressure without exceeding the coefficient 
of friction between the material of the wall and the surface upon 
which it rests. 

To resist the second tendency the weight above any joint 
must be sufficient to resist the pressure above the joint without 
exceeding the coefficient of friction of masonry upon masonry. 

The overturning moment of the earth pressure about the 
edge of rotation must be balanced by the moment of the weight 
of the wall and of the superimposed load about the same edge. 

The fourth condition applies only to retaining walls supported 
at their tops and built generally of concrete and steel. A retain¬ 
ing wall so supported would have to resist tension in one side 
and, as a masonry joint is not intended to resist tension, such 
construction involves the use of steel. Such construction is 
becoming more common on account of the saving in space due to 
the thinness of the wall. In Fig. 15G is shown such a wall. 
The tensile strength is supplied by the beams running horizontally 
and the twisted vertical rods. 

The resulting pressure due to the thrust of the earth and the 




160 


STEEL CONSTRUCTION 


weight of wall and superimposed load must fall within the base in 
order to give equilibrium, and within the middle third of the base 
to avoid tension on the masonry joints. Figs. 158-159 show 
types of retaining walls. 



Underpinning Shoring and Sheath Piling. Underpinning 
is the term given to the processes of carrying down old founda¬ 
tions or walls adjacent to new construction to the level of the new 
construction. 

It very often happens that footings of new buildings will be 
twenty or thirty feet below the bottom of the footings of the 
walls of an adjacent old building. To leave the old footings at 
this higher level after the excavation of the new building is 
made, would necessitate making the wall heavy enough to act as 
a retaining wall, to resist the pressure on the soil back of it. It is 
generally more practicable, therefore, to hold up the old wall 
temporarily by timber braces, needles, wedges, etc., and build new 
work up under it from the level of the footings of the new 
buildings. This new foundation under the old wall is called 
underpinning, and the construction necessary to hold it in place, 
during the process of underpinning, is called shoring. This latter 


















STEEL CONSTRUCTION 


1(31 


term applies to all bracing of old walls or adjacent construction 
during the construction of the new work, whether the wall is 
underpinned or not. 

Where a mass of eartli is to be held in place to enable new exca¬ 
vation to be made without disturbing it, heavy planks set edge to edge 
are driven down as the excavation proceeds, and braced at inter¬ 
vals by breast pieces or heavy timbers to keep the plank from 
bulging under the pressure of the earth. This construction is 
called sheath piling. The planks, generally, are pulled out after 
the wall, which is designed to permanently hold the earth in place, 
is built; sometimes, however, it is left in place. 

HIGH BUILDING CONSTRUCTION. 

Origin of the Types. Iron has been employed extensively 
in buildings for many years. The first building in this country 
of what is now known as the skeleton type of construction, was 
the Home Fire Insurance Company Building, built in Chicago in 
1883, of which Mr. W. L. B. Jenney was the architect. 

As this was an epoch-making event, it is important to know 
a few of the details of this building. In an account published in The 
Engineering Record of January 6, 1894, Mr. Jenney says: “The 
problem presented by them was to so arrange the openings that 
all stories above the second or bank floor could be divided to give 
the maximum number of small offices — say about 12 feet in 
width —each with its windows conveniently placed and sufficient 
to abundantly light the entire room. The work was planned 
quite satisfactorily, but the calculations showed that a material 
with very much higher crushing strength than brick was neces¬ 
sary for the piers. Iron naturally suggested itself, and an iron 
column was placed inside of each pier.” The chief departure 
was in making the columns bear all the loads, the walls between 
the piers supporting only their dead weight for a single story in 
height. Mr. Jenney states that the difficulty which was feared 
from the expansion and contraction of the iron columns led to the 
supporting of the walls and floors independently on the columns. 
The columns were of cast iron of box section, and the walls were 
supported on cast-iron box lintels, resting on brackets >n the 




162 


STEEL CONSTRUCTION 


columns. Tlie floor loads were carried by iron beams, although a 
few Bessemer steel beams were used, these being the first to be 
used in this country. 

Since the connections were by bolts, the beams were con¬ 
nected together by a bar running through the cast-iron columns, in 
order to secure a more rigid frame. 

The chief advance from that day is in the substitution of 
steel for all members in high-building construction, and in the 
development of details in the connections of the members. 

Types in Use. There are three main types of high build¬ 
ings : 

1. The class in which the exterior walls are self-supporting, 
and are designed also to support the ends of the girders carrying 
the floors. The floor loads inside the walls are carried by steel 
beams and girders framed between steel or cast-iron columns. 

2. In the second class, the exterior walls are self-supporting 
but the wall ends of floor girders are carried by steel girders and 
columns. 

8. In the third class, the steel frame is a complete unit in 
itself, and carries all floor loads, and, also, the load of the walls 
themselves. This latter is the pure skeleton type and the more 
common form of construction. 

Effect on Foundations. The different types have an impor¬ 
tant effect on the design of the foundations, and in some cases fix 
their character. 

In the first type, the benefit of isolated columns with inde¬ 
pendent foundations is largely lost, as unequal settlements in the 
walls themselves and in the walls and columns are likely to 
result. 

In the second type, as all loads are carried on columns which 
have isolated footings, more equal settlement will probably result, 
and in the event of the walls settling unequally with respect to 
the columns, would not affect the steel frame. 

In the third class all foundations are generally in effect of 
the character of isolated piers which can be proportioned to give 
nearly uniform settlements. 

When a party wall makes it desirable to keep all foundations 
inside of the building by means of a cantilever construction it 




STEEL CONSTRUCTION 


1(33 


can be more readily done in buildings of the third dlass than in 
any other type. ? 

Effect of Wind Pressure. Probably the most distinctive 
problem in liigli-building construction is the provision for lateral 
strains in the framework, due to wind pressure. The amount of 
these strains varies, of course, with the relation of the height of 
the building to the dimensions of its base and to its exposure on 
different sides. In the earlier designs, much more complete pro¬ 
vision was made for such strains than is now the practice. The 
laws of some cities, Chicago and Boston for instance, now limit 
the height to about 125 feet above the street. In other cities, 
notably New York, buildings of 350 feet or more are allowed. 
In New York, in buildings having an exposed height of four times 
or less the least dimension of the base of the building, no special 
consideration of wind strains is proscribed. 

In buildings where the walls are of solid masonry construc¬ 
tion and of moderate height, it is not necessary to consider the 
effect of wind pressure, as the dead weight of the masonry and 
the stiffness afforded by cross walls and partitions are sufficient to 
resist the effect of the wind, under ordinary conditions. With 
the light steel skeleton buildings carried to the height of the modern 
buildings, the elasticity of the steel frame makes it necessary, 
under certain conditions, to consider wind pressure. The walls 
being merely thin coverings, and the partitions also thin and not 
bonded to the walls, it is apparent that the frame itself must pro¬ 
vide all the resistance. 

The effect of wind blowing against the exposed surface of a 
building is 

(1) To produce an overturning moment tending to tip the 
whole building over, 

(2) To shear off the connections of the columns to each 
other, and to cause the floors to slide horizontally, 

(3) To slide the whole building horizontally on its founda¬ 
tion, 

(4) To twist or distort the frame. 

In buildings of usual proportions of height to base, the dead 
weight, even in the skeleton type, is sufficient to resist a bodily 
overturning. Some buildings have been built, however, that are 



164 


STEEL CONSTRUCTION 


almost of the character of towers or monuments, where this effect 
must he considered, and provision made for it, by anchoring to the 
foundations. The action under such conditions will be under¬ 
stood by referring to Fig. 160 which shows the outline of a nar¬ 
row building, having columns only in the walls. The building 
would tend to tip about the side opposite to that upon which the 
wind is blowing, and the columns on the wind side would be in 
tension, due to the action of the wind. If the load on these 
columns due to the weight of construction and a small percentage 
of-the live load, to cover weight of fixtures in the old buildings, 
were less than this tension, the difference would constitute the 
strain on the anchorage. If the building were safe against over¬ 
turning, it would ordinarily be safe against sliding bodily, as will 
be seen from the following consideration: 

Suppose a — the width of base 

h — the height above ground 
p = the wind pressure per square foot 
w = the dead weight necessary to resist overturning 
f the allowable coefficient of friction on the 
foundations 
b = length of building 

Then assuming the whole surface acted upon by the wind, and 
the weight of the building acting through its center of gravity 

p b h 2 

w — -— 

a 

In order, therefore, for the building of the above weight to slide 
/ w = p b h 

p b h a a 

^ p b h 2 A 

As the allowable coefficient can safely be taken at .40 this means 
that for the sliding tendency to be considered the width of base 
must be .40 or more of the height. 

Buildings in which the overturning effect would need to be 





ttoof (i/rder 



Diagram cf one Co/umn Bay 
Braced d/ftr rod} to res/d / 
/find Frejoum 


Fig. 16Q. 


STEEL CONSTRUCTION 


165 


TYPE5 OT WIND BRACING 




and (under} 





































































































































166 


STEEL CONSTRUCTION 


considered would have a base much narrower than .40 the height 
so that it is safe to say a narrow building, if safe against overturn¬ 
ing, would be safe against sliding. 

A further point in this connection is, that ordinarily, the 
columns do not stop at the ground level, but extend below and 
therefore have the resistance of the adjacent ground against 
sliding. 

The tendency to shear the connections, and to twist and dis¬ 
tort the frame, are ordinarily the most important features of wind 
pressure and these effects are always present in a high building 
exposed to wind. The connections necessary for framing the 
floors and columns may sometimes of themselves be sufficient to 
provide for these strains ; in other cases special provision must be 
made. 

Wind Bracing. Where special provision has been made it 
has generally been by vertical bracing between columns, either in 
the form of diagonal members, similar to the web members of a 
truss, or by portal bracing in the form of a stiffened plate arched 
between columns, or by knee braces between the columns and the 
horizontal members. A modification of the two latter forms has 
of late years resulted in using a deep girder at the floor levels, in 
the walls between columns. These different types of bracing are 
illustrated by Figs. 160 to 163. Their calculation will be con¬ 
sidered later. There is always some vibration in high buildings 
exposed to a severe wind, as has been shown by plumb lines hung 
in shafts from the top of the building. 

The wall covering being carried by the steel frame has 
greatly changed the methods of erecting a building. Now, the 
frame is carried up a number of stories, perhaps to its full height, 
before any work on the walls is commenced. It may then be 
started at the sixth floor just as well as at the first. The frame is 
also used as anchorage for the derricks used in erection. The 
designer or draftsman has, perhaps, little to do with the methods 
used in erection, but a.thorougli knowledge of the conditions and 
general practice which prevails should enable him to arrange the 
framing so as to facilitate and aid in the rapidity of the erection. 

It is not often that a complete system of diagonal braces can 
be used in the exterior walls, on account of interfering with the 



STEEL CONSTRUCTION 


167 


window openings; they are sometimes introduced in the interior 
walls or partitions. Portal bracing while formerly used to some 
extent is but little used now. Knee braces and deep stiff girders 
or struts at the floor levels, are the more common types of bracing. 
Portal braces, while forming a rigid frame without interfering 
with the openings inwalls, have the disadvantage of being difficult 
of erection, expensive, and they induce heavy bending strains in the 
portal itself and in the columns. 

Fig. 164 shows the Penn Mutual Building of Boston, during . 
construction, of which Messrs. F. C. Roberts & Co., and Mr. 
Edgar V. Seeler of Philadelphia were the architects arid engineers. 
This photograph shows the deep girders at each floor level which 
serve not only to carry the loads but as wind bracing. 

The student should also notice the method of supporting 
staging independently from any floor, and the masonry supported 
independently at each floor, as shown at the fourth floor. 

Figs. 165, 166, and 167 give interior views of the same 
building. The floor system was put in by the Eastern Expanded 
Metal Co. and consisted, in general, of a slab 7 inches thick re¬ 
enforced continuously at the bottom by 3-inch No. 10 expanded 
metal, and also at the top for about four feet from the ends. 
There were also j-incli round rods bent over the tops of the girders 
and running down to the bottom of the slab at the center; these 
rods were used every six inches. 

The span of these floor slabs is 17' — 6." 

These views show also the method of wrapping the columns 
and flanges of beams with metal lath and plastering. 

The student should note, also, the appearance of the ceriter- 
ing shown by Figs. 166 and 167, and of the concrete where the 
centers are removed; Hie grain of the wood is shown clearly 
marked in the concrete. % 

Fig. 168 shows the Oliver Building, Boston, during construc¬ 
tion, of which Mr. Paul Starrett was the architect. 

This photograph shows clearly the practice of leaving the 
masonry down for one or more stories and building the stories 
above. It also shows the iron fascias set in place in the upper 
stories; this is done in advance of the masonry so that the 
masonry will fit more accurately and neatly around them. 



168 


STEEL CONSTRUCTION 



Fig. 164. 















I 


/ 



Fig. 165 





















170 


STEEL CONSTRUCTION 



Pig. 166. 






























STEEL CONSTRUCTION 


171 



Fig. 16-7. 













172 


STEEL CONSTRUCTION 


The cornice brackets and framing are shown in place ready 
for the cornice when the building shall have reached this stage. 

niLL BUILDING CONSTRUCTION. 

This term must not be confused with “ mill construction.” 
The latter term applies to what is sometimes called “ slow burning 
construction.” This is a construction which is the result of the 
standardizing of requirements and recommendations of the Insur¬ 
ance Underwriters. It applies to a construction in which the 
walls are of brick, the interior posts of hardwood and of a size 
generally not less than 8 inches, the floor of heavy wooden 
girders with hard-wood floor timbers spaced about 5'— 0" center to 
center and 3" or 4" of hard-wood floor planks; while this con¬ 
struction is largely of wood the size of the timbers makes them 
slow burning to a certain degree. Modifications of this construc¬ 
tion in varying degrees exist, in which steel replaces some”of the 
wooden members, and from this to the all steel and brick construc¬ 
tion. In some cases the spacing of columns and required floor 
loads make it desirable to use steel or iron columns and steel 
girders, the floor beams remaining wood, however. In other 
cases crane loads and other special requirements make steel mem¬ 
bers more advantageous than the wood. The possibility of reduc¬ 
ing the brickwork to a minimum, by carrying all loads on a steel 
frame, and thus giving large window areas, caused a further 
development of the steel mill construction. Underwriters object 
to steel framed mills where the steel is left unprotected and thus 
exposed to speedy collapse in case of fire. The additional cost of 
fire-proofing generally results in its omission, however. 

Special Features. Mill building, and by this term is included 
machine shops and all classes of manufacturing buildings, must 
always be treated according to the requirements and conditions 
peculiar to the case. Details and capacities cannot be as well 
standardized as in the case of other classes of buildings, because 
there are generally features or combinations of features peculiar to 
the case. For this reason, the required loading should be accurately 
determined and the details carefully studied. Heavy loads should 
be brought directly on columns or over girders if possible, rather 
than supported by shelf or side connections. 




\\\\\ 


STEEL CONSTRUCTION 


173 



Fig. 168. 

















174 


STEEL CONSTRUCTION 


Where the building is of the shed construction, that is, with 
no floors or a very high first story, special provision for strains 
must be made. Trusses are generally connected rigidly through 
their whole depth and also by knee braces to the columns. Wind 
struts at the eaves and at intervals between these and ground are 
provided. A continuous brace at the ridge, and diagonal bracing 
in certain bays between the trusses is required. . With certain 
types of buildings, longitudinal trusses or braces between the 
main braces are also required. Before details of the different con¬ 
nections met with in this class of construction can be made, the 
student must become familiar with the general types of construc¬ 
tion. While only a few of the more common forms can be given, 
they will serve as a basis for more complete study of the different 
types. 

Figs. 169 to 174 show general features and details of a build¬ 
ing of the shed type. 

Fig. 169 shows the side framing, the openings, diagonal brac¬ 
ing, eave strut and columns. 

Fig. 170 shows a plan of the columns and trusses, and the 
bracing between. Fig. 172 shows the end-wall framing, and Fig. 
171 is a cross-section showing the type of trusses and the bracing 
to the columns. 

Fig. 178 shows a detail of the walls and the columns. These 
walls are for protection against weather only, and are not designed 
'to stiffen the steel frame which is sufficiently braced together 
itself. 

Fig. 174 shows the anchorage of the ends of the trusses if solid 
walls were used in place of the steel wall columns. 

Figs. 175 to 177 show a machine shop steel frame with pin 
connected trusses. Generally trusses of this character are riveted, 
but occasionally they are pin connected. 

Fig. 175 shows the cross-section with low wings along the 
side walls and a high central portion to provide room for a travel¬ 
ling crane. This central portion is lighted by a monitor at the top 
as shown; the windows in the end walls are also indicated* 

The columns are braced together and to the trusses and the 
whole frame is self-supporting. The crane runs on a track girder 
which is supported by a separate column. This is of advantage 



MILL BUILDING 

Brick h/a// for protection apa/hst h/eaf her on ]/. Diagram or Framing and Bracing 

Jfee/ Frame Se/p Jupport/rp. Scale j> l -o’. 


STEEL CONSTRUCTION 


175 




1 


CO 


Sv. . 

a bo 

* £ 


•5 
























































































































176 


STEEL CONSTRUCTION 



//o/F F/?ef Mew /fa//? fi/;//<///?p 

Fig. 175. 

























































































STEEL CONSTRUCTION 


177 


because it allows the column to be placed directly under the load 
instead of on a bracket which would cause heavy eccentric load¬ 
ing. 

Fig. 176 shows a partial elevation of the side. The columns 



are placed under every other truss only; the intermediate cross 
trusses are therefore supported by longitudinal trusses shown by 
Fig. 176. These trusses serve also to give the necessary lateral 
stiffness to the frame. 

Fig. 177 shows a detail of the ends of these trusses and the 





























































178 


STEEL CONSTRUCTION 


connection to the columns and of the bracing to the columns and 
trusses. 

Figs. 178 to 188 show the outlines and some details of a light 
mill building haying a double pitched roof as shown by the eleva¬ 



tion, Fig. 178. This elevation has letters indicating the positions 
of the different types of purlins shown by Figs. 179 to 182. 

As there are skylights on this roof, purlins 44 B” have special 
framing. The regular purlin is 44 A,” and 44 D ” shows the wind 
























GENERAL SECTION AND DETAILS 













































































































































































































STEEL CONSTRUCTION 


179 



Detail of Main Column 
Fig. 186. 






















































































180 


STEEL CONSTRUCTION 


struts between the columns; there is also a wind strut at the 
ridge. 

Fig. 183 is a detailed elevation of one-lialf of the main truss, 
and of the connection of the purlins to the truss. 

Figs. 184 to 187 show general features apd details of a com¬ 
bined wood and steel frame mill building. This form is used quite 
extensively. The main columns, trusses and girders are of steel; 
the roof purlins and floor beams of wood, and the walls of brick. 

Fig. 185 shows the detail for securing the wood purlins to the 
trusses. 

Fig. 186 shows the main column which carries a bracket for 
a light crane. This column, on account of the eccentric crane 
connection, is made of the two channels latticed as shown; in order 
to get a stiff connection of roof truss to the upper section of 
column, and also, because of the light load, a column of four angles 
and a web was desirable. This upper column, therefore, sets down 
inside of the channel column and is riveted to it as shown by the 
details. 

Fig. 187 shows the connection of the girders in the wings to 
the columns ; the double beams coming at right angles to the web 
made it necessary to use deep shear plates across the flanges of the 
column in order to give support to the bracket and provide for the 
eccentric strains. 














































» 














































/ 



























































LASALLE STATION, L. S. & M. S. AND C., R. I. & P. RAILROADS, CHICAGO 

View showing method of setting steel by hand. Note that the lifted column will rest on top of a column just above the floor line, seen 
to the right of the place where the lifted column rests on the ground. The bottom of the column rests between 
cover-plates, to which the column is riveted. The projection shown near top of lifted 

column is a bracket or shelf to receive a girder. 























STEEL CONSTRUCTION, 

PART'III. 


DEFINITIONS AND ABBREVIATIONS. 

In all structural steel detailing certain abbreviations are so com¬ 
monly used that it is essential at the outset for the student to be 
familiar with them. The more common are given below: 

PI. == Plate 

C = Channel. 

L = Angle. 

T = Tee. 

o = Round Rod, and when this mark follows a dimen¬ 

sion, as for example, f" o, it indicates a f'' diameter 
round rod. 

I I = Square. 

T. B. == Turnbuckle. 

O. H. == Open Hearth. 

R. W. = Roadway. 

S. W. = Sidewalk. 

R. & L. = Right and Left. 

Hex. = Hexagon. 

H. P. = Hard Pine. 

Y. P. == Yellow Pine. 

Bit. = Bolt. 

U. H. = Under Head. 

T. & G. = Tar & Gravel (also used for tongued and grooved h 

Tlie right meaning can generally be inferred from 
the place in which the abbreviation occurs. 

Riv. == Rivet or Rivets. 

Csk. = Countersunk. 

Cor. I. = Corrugated Iron. . 

Anch. = Anchor. 

Fill. == Filler. 




182 


STEEL CONSTRUCTION 


Str. 

— 

Stringer. 

F. B. 

= 

Floor 15 earn. 

C. I. 

= 

Cast Iron. 

Std. 

= 

Standard. 

Sepr. 

= 

Separator. 

W. G. 

= 

Wheel Guard. 

c. to c. 

— 

Center to Center. 

o. to 0 . 

= 

Out to out, or, outside to outside 

FI. 

= 

Flange. 

Lat. 

— 

Laterals. 

Diam. 

= 

Diameter. 

It. 

= 

Radius. 


The following definitions apply to pieces often met with in 
detailing and should be fully understood. 

Lag Screws, These are used for connecting wooden construc¬ 
tion, and their principal use, so far as the structural draftsman is inter¬ 
ested, is for fastening guard rails to plank flooring on highway bridges, 
or to cross ties on railroad bridges, or wood purlins on roof trusses. 

Fitting=up Bolts. This term is applied to bolts used to con¬ 
nect parts of a member, or to connect members to each other, prior 
to riveting. The bolts are removed and rivets driven in their stead. 
In making out the shop lists where work is to be erected, a number 
of these bolts must be included, and about 10% more should be 
ordered than will appear to be necessary, in order to allow for waste. 
Fitting-up bolts are used in the shop during the assembling of the 
parts of any member of a structure. 

Drift Pins. These are merely tapered steel pins used for 
aligning the rivet holes so that fitting up bolts may be inserted. 
Drift pins are also used in many cases to correct inaccuracies in the 
punching of the several parts of a member. If the holes do not 
match, so that the rivet can be driven through, the drift pin is first 
driven through and the edges of holes forced out so as to allow the 
rivet to be inserted. This is a use of drift pins which is not allowed 
by any first-class specifications, nevertheless it is often done, unless 
the shop work is rigidly inspected. 

Pilot Nuts. A pilot nut is a tapered end which is temporarily 
screwed on to the end of a pin in order to effect a passage for it 



STEEL CONSTRUCTION 


183 


through the pin holes of two or more members which are to be con¬ 
nected in the field. These are, of course, only needed in pin connected 
structures, but must not be overlooked in making out shop orders 
and shipping lists, and at least one must be sent for each size of pin 
used in the structure. 

Split Nuts. Owing to lack of room it is sometimes impossible 
to use a standard nut, and in such cases a thin split nut of about one- 
half the thickness of a standard nut may be used. 

Plate Nuts. For the ends of large pins the nuts are sometimes 
made from plate cut to hexagon shape and tapped out to fit the 
threads on the ends of the pins. 

Lomas Nuts. These are for use on the ends of large pins such 
as are used in bridge work. The pins are generally turned down 
to a smaller diameter at the ends, and these small ends threaded. A 
Lomas nut grips these threaded ends and projects over the shoulder 
of the pin. For dimensions and weights of Cambria standard pin 
nuts see Cambria Handbook, page 336. 

Clevis Nuts. On page 334 of Cambria Handbook are shown 
sketches of clevis nuts, and table giving dimensions, etc., is given. 
As will be seen in the sketch, the screw ends entering the clevis nut 
allow the effective length of rod to be adjusted. 

Sleeve Nuts. On page 333 of Cambria Handbook is found 
an illustration and table of dimensions, etc. The purpose of sleeve 
nuts, as will appear from the illustration, is to allow rods to be ad¬ 
justed as to their length when the ends are connected to pins or bolts. 

Turn buckles. An illustration of an open turnbuckle is shown 
on page 332 of Cambria Handbook. Turnbuckles are used the same 
as sleeve nuts. 

Tie Rods. Tie rods are plain rods with screw ends and nuts 
on each end, and they are used between the beams supporting fire¬ 
proof floors to tie the beams together and to hold them in position 
while the fireproofing is being put in place. The tie rods also stiffen 
the I-beams laterally. The sizes of rods used for this purpose are 
usually f-in. diameter to 1-in. diameter. See Fig. 207. 

Loop Eye Rods. Rods which are connected to other parts 
of a structure by pins are provided with loops made by bending the 
rod around to conform to a circle of same diameter as the pin, and 
welding the end into the body of the rod. The distance from the 




184 


STEEL CONSTRUCTION 


center of pin to the junction of the end of loop with the main rod is 
usually made about two and a half times the diameter of the pin 
which loop is to connect over. See Fig. 188. 

Forked Eye Rods. Sometimes it is desirable to have a rod 
connecting to a pin fastened so as to bring an equal strain on each 
side of another rod or part connecting to the same pin. In such 
cases it is necessary to make a forked eye instead of a single loop. 
See Fig. 188. 

Upset Rods. When rods are threaded at the ends, the cutting 
of the threads diminishes the effective area of the rod and conse¬ 
quently weakens it. To maintain the same strength throughout, 
the rod is “upset” at the ends before the ends are threaded, and 
the amount of extra thickness so provided allows the threads to be 

cut, and leaves after cutting a 
net area equal to that in the 
body of the rod. 

Upsetting- is done by a ma¬ 
chine which takes hold of the 
heated end of the rod when at 
a cherry-red heat and com¬ 
presses the metal for the re¬ 
quired length into a cylindrical 
end larger in diameter than the main body of the original rod. See 
pages 326 to 329 of Cambria Handbook. 

Plain Rod. The expression “plain rod” is simply the nega¬ 
tive of the term “upset rod”, which has just been refined, or, in 
other words, a “plain rod” is not upset. 

Standard Threads. Rods and bolts are generally provided 
with standard threads the dimensions of which will be found on 
page 316 of Cambria Handbook. 

Right=hand Threads. When the thread's of a bolt or rod 
are cut so that if, when looking at the end of the bolt or rod and turn¬ 
ing the nut from left to right, the nut moves from you, or is screwed 
on the threads, then such threads are referred to as right-hand threads. 

If the threads are cut so that the reverse is true then they are 
“left-hand threads”. 

Eye Bars. These are used in pin connected trusses and 
structures to take care of tensile strains. The heads at each end are 














STEEL CONSTRUCTION 


185 


formed by upsetting machines and the pin holes afterward bored out. 
See page 331 of Cambria Handbook for dimensions, etc., of standard 
eye-bar heads. 

Batten Plates. In Fig. 225 a batten plate is placed at each 
end of the strut on the top and bottom of the flanges. It is used 
merely to tie together the two parts of the strut. Batten plates (also 
called tie plates) are used generally wherever lacing is used in order 
to tie the parts of a member together at each end of the lacing. The 
Pencoyd Iron Works specifications for railroad bridges gives the 
following in regard to tie plates: 

“All segments of compression members, connected by latticing 
only, shall have tie plates placed as near the ends as practicable. 
They shall have a length of not less than the greatest depth or width 
of the member, and a thickness not less than one-fiftieth of the 
distance between the rivets connecting them to the compression 
members ”. 

Chas. Evan Fowler, in his Specifications for Roofs and Iron 
Buildings, refers to tie plates as follows: 

“Laced compression members shall be stayed at the ends by 
batten plates having a length equal to the depth of the members ”. 

The rules given in various specifications are somewhat different * 
as regards the length and thickness, being determined by each 
authority merely on his own judgment of what will prove satisfac¬ 
tory. There is no method of proportioning batten plates except 
in accordance with such specifications as may be furnished in rela¬ 
tion to the particular job of work in hand. 

Lacing. Single lacing is used on the girder shown in Fig. 225, 
but if two systems of lace bars are used crossing each other and 
riveted at their intersections, it is called double lacing This is only 
used on very heavy members. Single lacing is usually placed at an 
angle of about GO degrees with the axis of the member, while double 
lacing is placed at about 45 degrees to the axis. 

The size of lace bars to use is somewhat a matter of judgment, 
but certain rules have bedn established by common practice and 
experience which it is well to observe when practicable. Chas. 
Evan Fowler's specifications give the following: 

The sizes of lacing bars shall not be less than that given in the 
following table. When the distance between gauge lines is 



186 


STEEL CONSTRUCTION 


6 in. 

or 

less than 

8 

in. 

. li 

in. 

X } in. 

8 in. 

u 

<( 

{( 

10 

in. 

. H 

in. 

X i in. 

10 in. 

u 

a 

u 

12 

in.. 

. i! 

in. 

X x'd in. 

12 in. 

(( 

(c 

u 

16 

in. 

. 2 

in. 

X | in, 

16 in. 

(( 

u 

(( 

20 

in. 

. 2} 

in. 

X tV * n - 

20 in. 

u 

u 

(( 

24 

in.. 

. 2i 

in. 

X i in. 


24 in. or above,, use angles. 

They shall generally be inclined at 45 degrees to the axis of the 
member, but shall not be spaced so as to reduce the strength of the 
member as a whole. Where laced members are subjected to bend¬ 
ing, the size of the lacing bars shall be calculated, or a solid web 
plate used. 

Shop Drawings. In making shop drawings, the outlines of 
the member (in other words, the “picture” of it) should be done 
in fairly heavy lines, so as to show up clearly on the blue prints, 
and the dimension lines should be very light so that they will not be 
confused with the outlines of the members. All distances should 
be given from center to center, wherever possible. Dimensions 
from the edge of an angle, beam, or plate, should never be given 
unless there is a special reason for so doing; because all rolled shapes 
vary in the width of the flanges, and Z-bars also vary in height. The 
reason for this variation is that different sizes are rolled by the same 
set of rolls and the difference is made in the spacing of the rolls. 
See Figs. 25, 26, 27 of Part I. Also, angles of a thickness of one- 
half inch or more vary somewhat in the length of legs unless they 
are given what is called a finishing pass or rolling which is not always 
done. 

Make all drawings on the dull side of tracing cloth with a No. H H 
or a No. II H H pencil. After the drawing is completed the pencil 
marks are easily removed with a piece of sponge rubber. 

Do not draw out your work on paper first and then trace it. 
You will find that this is a waste of valuable time. Learn to draw 
directly on the tracing cloth, as you will be expected to do when you 
begin work in an office. You will need the following outfit in the 
way of drafting instruments and equipment: 

1 T-square, at least 20 in. long. 

2 Triangles, 1 of 45°, the other 60°. 















STEEL CONSTRUCTION 


187 


1 Small drawing board, about 18 by 24 in. 

\ dozen small thumb tacks. 

1 Ruling pen. 

1 Circular pen or spring bow pen. 

Tracing cloth. 

1 Triangular boxwood Architect’s scale 12 in. long. 

1 Bottle of Higgins’ American drawing ink. 

1J dozen Gillot’s pens No. 303. 

1 No. H H pencil. 

1 No. HHH pencil. 

1 Copy of Cambria Handbook, Edition 1904. 

PURPOSE AND USE OF DETAILS. 

A shop drawing is a drawing which gives all the information 
necessary to lay - out, cut, punch, and rivet the piece shown. It is 
the medium by which instructions are conveyed from the engineer’s 
office to the shop. It must convey full, accurate and explicit instruc¬ 
tions for every operation. It must be so clear and explicit that no 
further explanations are needed to enable the shop to correctly 
interpret it, and the information must be given in such form that 
only one interpretation is possible. The draftsman making a shop 
drawing must constantly bear in mind that the man at the shop will 
work entirely from this drawing; that he does not have access to the 
sources of information which are consulted by the draftsman in 
making the drawing, and that what might be clear in connection 
with these other drawings will be blind or uncertain to the shop man 
not familiar with them. The draftsman should further understand 
that it is distinctly the duty of the shop man not to read into the 
drawing anything not there, and that consequently the responsibility 
is entirely upon the draftsman to make his drawing so complete that 
such action will be unnecessary and impossible. Neatness in exe¬ 
cution of a shop drawing is desirable, but accuracy and clearness 
are absolutely essential. 

Shop drawings differ from general detail drawings in that they 
do not show the different parts of construction assembled, but cover 
only one piece. For instance, an engineer making a drawing to 
send to the drafting room where the shop details are to be prepared, 
would show a column with the girders and beams framing into it, 



188 


STEEL CONSTRUCTION 


just as they would appear when assembled. In this way he would 
establish the relations of the different members and would determine 
the character of the connections and any special features of the 
details. The draftsman detailing for the shop, however, would make 
the column on one sheet, each beam and girder on separate sheets, 
and the different members forming the whole structure would appear 
only as individual pieces, their relations one to the other being given 
by an assembly or erection drawing. 

In a large shop the columns, beams, and girders would be fabri¬ 
cated in entirely distinct departments and the men in the different 
departments would not know that those different pieces when assem¬ 
bled, fitted into each other. The responsibility for correctly laying 
out these pieces so that they will fit together is upon the draftsman. 

Measurements on shop drawings are always carried out as 
close as one-sixteenth of an inch, and sometimes to one thirty-second. 
An error of one-sixteenth may be sufficient to make it impossible to 
assemble the pieces in erection, as steel cannot be cut and drilled 
at the building except at considerable expense of time and money. 
Such errors are costly. 

The student should clearly understand the importance of the 
work of the shop draftsman and should always be imbued with the 
idea that he is the last authority to pass upon all the various points 
determining the instructions of the shop and the last sentinel to dis¬ 
cover and prevent errors. Drawings are almost always checked by 
some other than the man who makes them, but no man will make a 
successful draftsman unless he does his work without a thought of 
being saved from errors by the checker. 

The making of templets, and the way in which a shop uses a 
detail drawing have already been explained. The draftsman should 
always detail as far as possible, in accordance with standard shop 
practice, as in this wa ,y much templet work can be eliminated and 
thus time and expense saved, and the work will be more quickly 
fabricated because of the familiarity of the shop with the details. 
The standard forms differ somewhat in the different shops, but the 
Carnegie standards are essentially the same as all others; these have 
been given in Steel Construction, Part I. A great many conditions 
arise in which standard forms cannot be used, in which cases as 
simple details as practicable should be employed. 




STEEL CONSTRUCTION 


189 


Scales Used in Details. Details of plate and box girders 
and of trusses are almost invariably made to scale, generally f, 1 or 
1J in. to the foot. Details of columns are generally made to scale as 
far as the connections for beams and the head and foot of columns 
are concerned. The length along the shaft from top to bottom and 
between connections at different levels is generally not to scale. 

Details of beams are rarely drawn to scale, but the position of 
holes and of shelf angles, etc., are shown in the proper relation to each 
other and to the whole beam. That is, if the beam shown is a 12-in. 
beam 16 ft. long, the elevation of the beam might be drawn to a 
scale of 1J in. to the foot as regards the height of beam, while as 
regards the length it might be drawn at no definite scale, simply 
made to come within the limits of the sheet. In locating holes in 
this elevation, if there was a horizontal line of holes in the center 
of the beam it should show in the center of space limiting the height 
of beam; if another line 2 in. off from the center, it should be shown 
at J of the depth from the center line. Similarly to spacing holes 
along the length of the beam a set of holes centrally located as regards 
the length should show in the center of the sketch, and another set 2 
ft. from the center should show g of the whole length from the center. 

In other w T ords, the beam is detailed according to the scale of 
the sketch which represents the beam, but this will not be the same 
scale vertically as horizontally and will not be the same scale for any 
two sketches. 

The reason for the above absence of scale in beam sketches 
is that these details are almost invariably made on a standard size 
of sheet, say 12 X 18 in. One sheet may have beams varying in 
depth from a 7-in beam to a 15-in. beam, and in length from 6 ft. 
to 20 ft. To accommodate all such varied conditions to the same 
size sheet it is necessary to adopt a standard size of sketch repre¬ 
senting all sizes and lengths of beams, and locate details on this 
sketch simply by the eye, so as to show the details in proper relations 
as outlined above. In many drafting offices these beam sheets are 
printed with a blank elevation and plan and end view of a beam 
ready for the draftsman to fill in the details. 

In the case of columns, girders and trusses, this practice would 
not do, as the details are too complicated and it is necessary to show 
all details exactly in their true relation in order to make them clear. 



190 


STEEL CONSTRUCTION 


In the case of columns this can be done on a standard size sheet, 
generally 12 X 30 in. or 18 X 30 in. Girder sheets and truss sheets 
generally vary in size with the particular conditions of each case. 

The first operation necessary is to draw out the outlines of the 
member to be detailed, showing a side elevation and plan, or end 
view and sections where necessary to clearly show all the work to 
be done. Make no unnecessary drawing; as, for instance, if a side 
elevation and plan will clearly express all the work to be done, do 
not spend any time making an end view or sections. If, on the 
other hand, an elevation and a cross section will enable you to show 
everything, then do not make any plan, as, in general, it is less work 
to make a cross section than a plan. 

The above should be followed with caution, as it is necessary to 
be very sure that all the views required to give a clear understanding 
of the details are given. 

Rivet Holes, Etc. Holes for rivets are either simply punched, 
or punched to a smaller size than that actually required and reamed 
out to the full size, or else the holes are drilled. Rivet holes are 
seldom drilled, except under special specifications, owing to the 
increased expense. On almost all work at present the holes are 
simply punched. In case reaming or drilling is required the shop 
drawing must indicate it clearly. 

Where the holes are simply punched the usual specification is 
that the diameter of the punch shall not exceed the diameter of the 
rivet, nor the diameter of the die exceed the diameter of the punch 
by more than one-sixteenth of an inch. 

Where the holes are punched and afterward reamed, the usual 
specification is “All rivet holes in medium steel shall be punched 
with a punch \ in. (sometimes T 3 ^ in.) less in diameter than the 
diameter of the rivet to be used, and reamed to a diameter X V in. 
greater, or they may be drilled out entire ”. 

The effective diameter of the driven rivet shall be assumed the 
same as before driving, and in making deductions for rivet holes in 
tension members, the hole will be assumed one eighth of an inch 
larger than the driven rivet. 

The pitch of rivets is generally specified about as follows: “The 
pitch of rivets shall not exceed sixteen times the thickness of the 
plate in the line of strain, nor forty times the thickness at right angles 



‘STEEL CONSTRUCTION 


191 


to the line of strain. The rivet pitch shall never be less than three 
diameters of the rivet. At,the ends of compression members it shall 
not exceed four diameters of the rivet for. a length equal to the width 
of the members.” 

Rivets and Riveting. Rivets are spoken of as*“shop rivets” 
or “field rivets” according to whether they are to be driven in the 
shop or in the field during the erection of the work. It is sometimes 
impossible to drive rivets by machine in the shop, owing to their 
location being inaccessible for the riveter. In such cases they must 
be driven by hand and are referred to as hand-driven rivets. Driving 
rivets by hand is necessarily more expensive than if done by ma¬ 
chinery, and it is part of the duties of a competent structural drafts¬ 
man to so design the details as to require the least possible driving 
of rivets by hand, whether in the shop or field. In erecting large 
jobs the field riveting is often done by machine riveters. There are 
numerous types of machine riveters, the principal power used being 
either compressed air or hydraulic power. 

In order that rivets may be driven by the riveting machine it is 
necessary to have a certain amount of clearance from the heads of 
other rivets which project from the other leg of an angle if the two 
rivets are opposite or nearly opposite each other. This is shown in 
Fig. 189, together with a table giving sizes of rivet heads and clearances 
for machine driving. At the bottom of this table please note that a 
must not be less than J in. + ^ h. Suppose we wish to drive two 
rivets, each f- in. diameter, and both to have full heads exactly in 
the same line in the two legs of an angle. Now, if we desire to know 
how close we can drive the rivet in the horizontal leg to the back 
of the angle, we first find the value of h for a J in. rivet, which is 
lyV in. Then a = } in. + J (1 T \ in.) = f f in. Add this to the 
height of the rivet, which, for a f- in. rivet is f f in., and we have 
If in. as the distance from the center of the rivet in the horizontal 
leg of the angle to the side of the vertical leg of angle nearest to this 
rivet. But all measurements to locate the position of rivets are given 
from the backs of angles; hence we must add the thickness of the 
angle in order to find where the rivet in the horizontal leg should be 
spaced. Suppose the angle to be f in. thick, then If in. + J in. = 2 in. 
would be the least distance from the back of the angle that we could 
drive either rivet in order to have the riveting machine clear the other. 



192 


STEEL CONSTRUCTION 


Rivets could, however, be spaced nearer to the back of the angle 
if the rivets are “staggered”, i.e., if those in the vertical leg were 
spaced so as to come in between the two adjacent ones in fhe hori¬ 
zontal leg. An example of staggered rivets is shown in Fig. 233. 

Conventional Signs. In erecting some classes of structural 
steel work, especially in light highway bridges and small roof truss 
jobs, the connections are often made with bolts instead of rivets. 
The rivets used for structural steel work are round headed (some¬ 
times called “button head”) rivets. It is necessary sometimes to 
flatten the heads of rivets after the rivet is driven, and before it has 


-- SHOP- -H j<—- —FIELD --— 



w 

V* A 


to- 

£ 

- ~xd - 

- >4 “ 

- ® - 

- M. 

!&r 



r/ // / I*r_ 





TWO FULL 
HEADS 

/WU rULL r- 


- LUU/V1 L.fizOL//vn 



-0 M = 

E g= 






£2 >aL 

ay _ rt _ ok 

_ ay _ A? 

^ y-j w up 


FLATTENED TOi 

OF COUNTERSUNK* 

AND NOT CHIPPED 
-Q----n- 

FLATTENED Tof 

r\ — 

FLATTENED Tof 

-O-«-- 

^ — 0 ~ 

*— 1 W '—’ 



Fig. 189. 


had time to cool. This is done by simply striking the red hot head 
of the rivet and flattening it to the extent desired. Wherever a flat¬ 
tened head would interfere with some connecting part of a structure 
it is necessary to countersink the heads, sometimes on one end of 
the rivet and sometimes on both ends. Fig. 189 shows conventional 
signs for representing the different kinds of rivet heads desired, and 
this code is in general use in the United States. 

It is very important to show on all shop drawings the diameter 
of rivets to be used in the work, and if different sizes of rivets or rivet 
























STEEL CONSTRUCTION 


193 


holes for field rivets occur in the same member, then these must be 
indicated on the drawing by a note prominently displayed so that 
the shop men may readily find it and avoid error. The sizes of 
rivets generally used for structural steel and bridge work are -J in., 
f in., or | in. in diameter, although special work may require smaller 
sizes, and occasionally rivets 1 in. in diameter are used for very 
heavy work. 

Rivets are made with one head formed, and the shank of the 
rivet must be long enough to project through the parts to be* joined, 
and far enough out on the other side to form a full perfect head when 
subjected to the pressure of the machine. After the rivet has been 
heated to a cherry red it is inserted in the rivet hole and the riveter 
is placed so that the cap fits over the head already formed, and the 
other jaw of the machine presses against the protruding shank of the 
rivet and forms the head. It is desirable that riveting machines be 
made to hold on to the two ends of the rivet with the full pressure 
until the rivet partially cools. 

The terms “rivet pitch” and “rivet spacing” refer to the dis¬ 
tances center to center between rivets. For example, if the rivets 
are spaced 3 in. apart for a certain distance along a member of a 
structure, w r e refer to the rivets for this portion of the member as 
being of three-inch pitch. Fig. 190 gives the lengths of rivets re¬ 
quired for a given “grip”. 


PROBLEMS. 

1. Given an 18-in., 55-lb. I-beam with a 4 X 4 X 4-in. shelf 
angle riveted on one side; what length of J-in. rivet should be ordered 
for riveting this angle on in the field ? 

2. In Fig. 187 of Part II, is shown a 12-in. beam girder bolted 
to a cap angle on a column; what length of bolts should be ordered 
for this connection? 

3. If the beams shown in Fig. 187 are 6? in. center to center, 
and are bolted up, using standard cast iron separators, what lengths 
should be ordered for these separator bolts ? 

4. Suppose a 12-in., 40-lb. beam and a 7-in., 15-lb. beam are 
framed opposite each other on a 15-in., 60-lb. girder; if standard con¬ 
nection angles are used, what length of f-in. field rivets should be 
ordered for the connection of the beams to the girder? 



194 


STEEL CONSTRUCTION 



Fig. 190. 


















































































STEEL CONSTRUCTION 


195 


5. If it is necessary to drive two rivets of f in. diameter exactly 
opposite in the two legs of an angle 3 X 3J X x 7 6 in.; how close 
to the back of the angle can the rivets be spaced ? 

Strength of Joints. The student should now become famil¬ 
iar with the method of calculating the strength of joints and connec¬ 
tions. We will take first the connection of one beam framed to 
another. The rivets in the connection, of course, are the only means 
of transmitting the load from the beam to the girder. There are 
two sets of these rivets, one set through angles on the end of the beam 
to be carried and the other set through the outstanding legs of these 
angles and through the web of the girder. The load must go from 
the beam through the first set of rivets into the connection angles, and 
then from the angles through the second set of rivets into the girder. 

The rivets through the angles securing them to the web of the 
beam are subject to failure in two ways. (1) The rivet might break 
along the two planes coincident with the faces of the web of the beam, 
thus allowing the beam to drop between the two angles—this method 
of failure is called “ shearing” of the rivets. (2) The rivets might 
crush the metal of the web of the beam on the upper semi-circumfer¬ 
ence of the rivets; this is called failure by “bearing.” 

In designing a connection, the number of rivets is determined 
by whichever provision against these two methods of failure gives 
the greatest required number. The strength of a rivet as regards 
shearing and bearing is called its value, and in order to determine 
the number of rivets to carry a given load in connections of this 
character, it is only necessary to determine the value to be used for 
one rivet. This value is determined in the following way: 

DETERMINATION OF SHEARING VALUE OF RIVETS. 

The resistance of a rivet to shearing along one plane is the area 
of the rivet multiplied by the shearing strength of the metal per unit * 
of area. 

If d — the diameter in inches of the rivet 

S = the ultimate shearing strength in pounds per sq. in. 
then V = the ultimate shearing value in pounds. 

= .7854 d 2 ,S. 

For the working value of the rivet a certain proportion of S is 
used and this varies with the factor of safety required. The safe 



196 


STEEL CONSTRUCTION 


value of the shearing strength per square inch of power-driven rivets 
which is generally used for buildings, is 9,000 pounds, which gives 
a factor of safety of about six. With rivets three-quarters of an inch 
in diameter, which is the usual size in building work, the safe shear¬ 
ing value is therefore 

.7854 X |X|X 9000 = 397G pounds. 

For rivets driven by hand as is done in many cases in assembling 
the parts in the erection of a building, the safe shearing strength per 
square inch is reduced to 7,500 pounds. One of the connections 
illustrated in Fig. 191 is a case of double shear for the rivets through 
the angles and the web of the beam, as there are two planes along 
which shearing must occur, since the load is distributed by the web 
of the beam equally between the two angles. The above value of 
3,976 must be multiplied by two to give the total resistance of each 
of these rivets against shearing. 

The rivets, however, which go through the outstanding leg of 
these angles, and through the web of the girder which carries this 
beam are only in single shear, as here there is only one plane between 
the angles which transmit the load and the web which receives it. 
The value for these rivets would therefore be 3,976 lb. if power driven, 
and 3,313 lb. if hand driven. 

DETERMINATION OF BEARING VALUE OF RIVETS. 

In this case it is the metal which bears on the rivet or which the 
rivet bears on, which has to be considered; this is in compression 
and liable to failure, therefore, just as is the metal in a column or the 
compression side of a girder. The amount of stress which this 
metal will stand is determined by the ultimate compressive strength 
per square inch, and the area under compression, which area is the 
product of the diameter of the rivet and the thickness of the metal 
or in this case, the web of the girder. 

If therefore t = thickness of metal 
d — diameter of rivet 

C = ultimate compressive strength in pounds per 
square inch, 

V b === ultimate bearing value in pounds 

= C dt 


then 



STEEL CONSTRUCTION 


197 


The safe value usually used for power-driven rivets in building 
work is 18,000 pounds per square inch; for three-quarter-inch rivets, 
therefore, the bearing value becomes for a x 5 ^-in. web 18,000 X J X T 5 6 
= 4,219 pounds, and for hand-driven, rivets, 3,516 pounds. 

The web of the beam in Fig. 191 is a case of bearing enclosed, 
that is, it is enclosed on both sides by other members, and therefore is 
stiffened against buckling under compression. The web of the 
girder is not enclosed, as it is free to buckle on one side. Most 
authorities allow a slightly greater bearing value, generally about 
10 per cent for bearing on metal enclosed. 

In designing such a connection as is illustrated in Fig. 191, 
the number of rivets through the web of the beam would be deter¬ 
mined by the bearing value of one rivet, unless the thickness of this 
web was f in. or over, since for all thicknesses less than this the bearing 
value would be less than the double shear. The number of rivets 



Fig. 191. Fig. 192. 


through the web of the girder would be determined by the shearing 
value of one rivet for all thicknesses of webs of T 5 g in. and over, since 
for these thicknesses the bearing value is greater than single shear. 
Where two beams frame into a girder on opposite sides so that the 
rivets through the girder are common to both beams as shown in 
Fig. 192, these rivets are in bearing on the web of the girder for the 
combined load brought by both beams, in double shear for the com¬ 
bined loads, and in single shear for the load from each beam. If 
these loads were the same for each beam, single shear from the load 
from one beam would, of course, be equivalent to double shear for the 
load from both beams; if, however, the loads were greatly dissimilar 
the greatest load with the single shear value must be used. To 
illustrate this, suppose we have a 10-in. beam framed on one side of 
a 10-in. beam and an 8-in. beam framed opposite to it. Suppose 
the load brought by the 10-in. beam to the girder is 14,000 pounds, 

























198 


STEEL CONSTRUCTION 


and that by the 8-in. beam 6,000 pounds. Now the web of a 10-in. 
25-lb. beam is .31 inches thick, and the bearing value would therefore 
be .31 X 15,000 X .75 = 3,487 pounds, and for the total load this 
would require six rivets. To carry the load of 14,000 pounds in single 
shear at a value of 3,313 would require but five rivets, so that the bear¬ 
ing value and the total load from both beams would determine the 
number of rivets. 

If, however, these beams were carried by a 12-in., 40-lb. beam 
whose web is .46 inches thick, the bearing value would then be 5,175 
pounds and this would require but four rivets; in this case the number 
would be determined by the greatest load and the single shear value 
of a rivet. Fig. 193 shows a single angle connection which would 
be determined by the rivet in single shear. It should be noticed 
that in designing connections a few rivets in excess of the actual 
number calculated should be used for connections; in general, 20 per 
cent should be added. 




PROBLEMS. 

1. Suppose that certain rivets to be provided in a connection 
are in double shear. The rivets are all J in. in diameter. The out¬ 
side plates are each \ in. thick. What will be the thickness of the 
inside plate to make the rivet value equal to double shear ? 

2. Suppose a 6-in., 12.25-lb. I-beam that is 5 ft. long carries a 
load of 15,000 lb., uniformly distributed. How many rivets } in. 
in diameter, will be required for its connection to the beams at each 
end, allowing 6,000 lb. per square inch for shear on the rivets, and 
12,000 pounds per square inch for bearing? 

3. In the preceding problem, how many rivets J in. in diameter 
will be required to attach the connection angles to the 6 in. I-beam? 
In order to determine this, it will be necessary to first find the thick¬ 
ness of the web of the 6-in., 12.25-lb. I-beam. This can be found 
by referring to the tables on pages 30 and 31 of Part I. As the 















STEEL CONSTRUCTION 


199 


thickness of the webs is there given in decimals of an inch, these must 
be converted into the next smaller commoi) fractions. 

4. Given a 12-in., 31J-lb. I-beam 14 ft. long and a 10-in., 
25-lb. I-beam 12 ft. long framed opposite to each other to a 15-in., 
42-lb. I-beam. If these beams are each loaded to the safe capacity 
with a uniformly distributed load, what will be the number of f-in. 
rivets required for the field connection to the girder, using 7,500 
pounds for shear and 15,000 pounds for bearing? 

5. In the above problem what will be the number of f-in. shop 
rivets required on the end of each beam using 9,000 pounds for shear 
and 18,000 pounds for bearing? 

6. Using the same values and loads as in problem 4, what 
will be the number of rivets required in each beam, if they do not 
frame opposite each other? 

7. Give the lengths of field rivets and shop rivets required for 
each connection in each of the cases covered by problems 2, 3, 4, 5, 6. 

STANDARD CONNECTIONS. 

As previously stated, beam connections to girders and columns 
are generally made after standard forms for the different size beams. 
From an inspection of these standard connections it will be seen 
that 3, 4, 5, and 6-in. beams and channels all have the same number 
of rivets; 7, 8, 9, and 10-m. sections have the same number; and of 
the larger beams the different weight beams of a given size have the 
same number, whether the lightest or heaviest section is used. It is 
evident that these beams which are of different capacities, would 
not require the same number of rivets, if the number was calculated 
for the exact load of each case. It would not be economical, either 
from the standpoint of time or money, to detail in this way, however, 
and therefore these standard forms are always used unless peculiar 
conditions made it impossible to frame with these size angles, or unless 
because of peculiar conditions of loading, these connections would 
not be sufficiently strong. 

These standard connections are proportioned for uniformly 
distributed loads with spans commonly used for the different size 
beams. When beams are used on short spans and loaded to their 
full capacity, it would be necessary to design special connections with 
the required number of rivets; the same is true where a concentrated 




200 


STEEL CONSTRUCTION 


load comes on a beam very near to one connection. The tables on 
pages 42 and 43 of the Cambria Handbook give the minimum spans 
of the different size beams and channels for which these standard 
connections can be used when the beams are loaded uniformly to 
their full capacity, based on 10,000 lb. per sq. in. for shear and 20,000 
lb. for bearing. For cases of concentrated loading near the ends, 
no general rule can be given. For all cases of loading on spans 
shorter than those given by the table, the draftsman should calculate 
the load on the connections and determine the number of rivets 
required. 

Connection angles are always riveted to beams centrally as 
regards the depth of web unless conditions make it necessary to raise 
or lower them. Such conditions arise when certain beams of differ¬ 
ent depths frame opposite to each other to the same girder. There 
are standard conditions concerning many of these cases and these 
are shown in Figs. 135 to 139, Part II. Such connections should 
be made by changing the position of the angles rather than the spac¬ 
ing of the holes in the angles if possible, so that the standard'framings 
can be used. 

Where beams frame on opposite sides of the same girder, but the 
center lines of the two beams do not lie on the same straight line 
special size angles and rivet spacing is required. If the distance 
between the center lines of the beams is less than 8J in., as shown 
in Fig. 194 the one line of rivet holes must be common to both beams. 
The minimum distance between rivets of beams framed to the same 
side of a girder for which standard connection angles can be used is 
shown in Fig. 137. In cases where beams are spaced closer than 
this, a single angle with the required number of rivets is used in the 
outside of each web; or where there is sufficient depth of girder a 
shelf angle below the beams can be used. In this case stiffeners 
fitted to the outstanding leg of the shelf angle should be used, as under 
deflection the beam will bear near the outer edge of angle and without 
the stiffeners would tend to break off this leg. The full number of 
rivets required to carry the load should be put in the stiffeners and 
shelf, even if angles on the web of the beam are used to hold it laterally. 
It is not good design to rely on the combined action of two sets of 
connection's, such as a shelf connection described above, and a web 
connection, to carry a load. In such a case the, deflection of the 



STEEL CONSTRUCTION 


201 


beam would bring the bearing on the shelf, and this connection would 
take the whole load; or if the shelf was not stiffened to resist bending 
under the load, this would throw the load on the web connections. 
Wherever a shelf with stiffeners is used it should contain enough rivets 
for the full load. 

Where beams frame to deep girders or to columns, even if the 
connection is made by angles on the web of the beams, it is customary 
to put a shelf angle under the beam. The student should not confuse 
this construction with the one just described. The object of’such a 
shelf is to facilitate erection and not to support the beam after the web 
connection is made. Where such an angle is used, therefore, no 
stiffeners should be used under the beam, as these would prevent 
the web connection from performing the work for which it was de¬ 
signed. The draftsman must see that the connection angles are not 
placed so as to interfere with the fillet of the beam or of the girder. 
This consideration arises where the connection is raised or lowered on 
the beam, or where the beam does not frame flush with the girder, 
or where a small beam frames flush with a large one, as for instance 
a 5-in. beam to a 24-in. beam. Fig. 36, Part I, gives rules for deter¬ 
mining the distance from outside of the flange to the commencement 
of the fillet. These distances are given also in the Cambria Hand¬ 
book. It is possible to encroach a little on the fillet but generally 
not more than J in. 

The standard form of connections of beams to columns is by a 
shelf angle with the stiffeners under it, with the required number of 
rivets, and with a cap angle over the top. The beam is riveted both 
to the cap and the shelf angles. Generally there are four rivets in each 
flange—sometimes only two in each flange are used. The shelf 
angle is usually a 6 X 6 X ^-in. angle and the cap angle a 6 X 6 X T V 
in. angle where four rivets in the flange are used; if only two rivets 
are used the outstanding leg would be 4 inches instead of 6 -inches. 
The size of stiffener angles varies with the size necessary to conform 
to the rivet pitch of the column, and to keep the outstanding leg of 
the stiffener the required distance from the finished line of the column. 
As stated previously, the deflection of the beam tends to throw the 
load near the outer edge of the angle and therefore the stiffener 
should come as near this edge as is practicable. Another point to 
be considered in choosing the size of stiffeners is to bring the out- 



202 


STEEL CONSTRUCTION 


standing leg as near as practicable under the center of the beam as 
this is the portion of the shelf loaded by the beam. It is riot always 
practicable to do this, however, and sometimes two stiffeners are used 
coming a short distance each side of the center of the beam. 

A good many designers use only one stiffener under a beam or 
girder, and as the load to the stiffener comes from the outstanding 
leg, this brings a moment on the rivets through the other leg of the 
stiffener. For usual sizes of beams, there is probably ample strength 
in the rivets to provide for this moment. It is better design, how¬ 
ever, to use two stiffeners back to back, with rivets connecting the 
outstanding legs, as shown in Fig. 217. This avoids the strain due to 
the moment on the rivets and also distributes the load to the column 
symmetrically with regard to the axis, instead of entirely on one side. 
These points are of very great importance where heavy girders or 
unusually heavy concentrated loads are concerned. Special column 
connections will be taken up later on. 

The connections of beams to double beam girders, involve the 
consideration of a number of practical points peculiar to each case. 
These beams are generally bolted together with only a slight space 
between the flanges, and if the girder rests on a column, the holes 
must be arranged where they are accessible. In general this would 
be in the outside flanges unless the end of the girder was exposed so 
that the inside flanges could be reached. 

Where beams frame to such a girder they cannot be riveted 
unless it is possible to rivet all the lines of such connections to each 
beam comprising the girder before they are brought together and 
bolted up. Where there were several lines of such girders it would 
be difficult to do this for all of them. In many cases, therefore, 
these connections have to be arranged for bolts to go through both 
beams of the girder. Where double beam girders frame into another 
girder the connection can only be made by single-angles on the outside 
of the webs, unless the beams are spread far enough apart to allow 
bolts or rivets on the inside to be reached. If the girder carrying 
the double beams is deep enough a shelf connection can of course 
be used, and this would be preferable to the single-angle connection. 

Connections by angles on only one side of the web, as shown 
in Fig.-193, should always be avoided if possible, as they are subject 
to a bending moment on the rivets in the same Way noted for single 





STEEL CONSTRUCTION 


203 


stiffeners. Where such a connection must be made sufficient extra 
rivets should be used to provide for this moment. The remarks in 
regard to double beam girders apply also to girders made up of three 
and four beams. In these cases, however, there must be room for 
connection angles on the inner beams, and if the connection cannot 
be made when the beams are bolted together, it must be arranged 
so that these beams can be erected before the outside ones. In such 
an arrangement it is obvious that the standard form of cast iron plate 
separators could not be used very readily unless rods were used through 
the separators instead of bolts. 

In Fjgs. 131 to 140, Part II, are shown cases of special framing 
to which the student should refer again and become thoroughly 
familiar with. 

Where different sizes of beams frame opposite to the same girder 
it is necessary to change the position of the framing angles on the 
beams in order to use standard connections in each case. These 
changes in position are generally made to conform to standard prac¬ 
tice, which is illustrated in Part II and which in general is as follows: 
In all cases except where one of the beams is a 7-in. beam, the first 
hole is 3J in. from the flanges which are flush with each other, and 
standard angles are used. Where one of the beams is a 7-in. beam 
and the other is either a 6,8, 9,10 or 12-in. beam the first hole is 2\ 
in. from the flush flanges; for a 12-in. beam the first hole is 2f in. 

Fig. 190 shows the Carnegie code of conventional signs for rivets. 
It is important to follow the code in use by the particular shop for 
which the drawings are intended, as only by the use of such signs can 
elaborate notes be avoided. 

Illustrations of Details. Fig. 195 shows a detail of a 
punched beam. Note that there should always be a single overall 
measurement on the sketch. Groups of holes, as for instance holes 
for connections of other beams, as shown in the top flange and the 
web, are located by fixing the center of the group. The reason for 
this is that the beam on which is the framing connecting to the holes 
is located by its center, and therefore it is important to locate this 
exactly. If the holes are symmetrical with regard to the center it is not 
necessary to dimension each hole from the center, but simply to give 
the distance between them, corresponding with the distance in the out¬ 
standing legs of the connection angles on the beam framing to this one. 



204 


STEEL CONSTRUCTION 


In the case of a channel it is the back of web rather than the 
center which is always located. For the holes for connections of a 
channel, therefore, the position of the back of channel is fixed, and 
then each hole in the group forming the connection must be located 
with respect to the back of channel as the group is not central with 
regard to the back. For an example of this see Fig. 196. It always 
adds to the clearness to put near each group of holes forming a con¬ 
nection for other beams the size of beam or channel connecting to it. 
Holes at ends of beams for connecting to columns or for anchors 

fill Open Holes M 
3 t Paint One Coat 



4-/2"~3/.5*Beams //-4"/onq o.a. Ms?&k ' ‘?nd. Floor' < 7los.-3I, 74. 96.108. 

Fig. 195. 

are generally spaced by an independent set of measurements from 
the end of the beam. 

The student should note that beams cut by the mill without 
special directions being given are subject to a variation in length of 
f in. under or over the length specified. If the beam rests on walls 
such variation is unimportant. If, however, it frames between col¬ 
umns and has holes connecting to the columns, such variation could 
not be allowed. For this reason measurements of such beams should 
always be marked “exact” or else at end of the sketch should be 



















































STEEL CONSTRUCTION 


205 


printed “column end Jin. clearanceWith such instructions, or 
similar directions in other cases to indicate how the beam rests with 
respect to other work, the mill will take the necessary precautions. 
In the case of framed beams, for instance, such notes are not neces¬ 
sary, as it is self-evident that no variation at these ends can be allowed. 

Fig. 196 shows a beam framed into another beam, the relations 
of the top and bottom flanges being such as to avoid coping. Note 
here that it is necessary to give an end view to show the spacing of 
holes in the outstanding legs of connection angles. Note also the 


fill Qiuets /' 

,« fill Open Holes % 

* PainI One Coat 



6- 8 : /8 T dearns -/F7/'/g. oa Mrer First Floor ffos'z/-z6 incl. 

Fig. 196. 


specification as regards these angles. If the connection is standard 
and is placed centrally with the beam, always say “ standard connec¬ 
tion”. In such cases if the shop is familiar with the standards re¬ 
ferred to, an end view is not always necessary. If the connection is 
not placed centrally with the beam, or if the spacing of the holes in 
the legs varies any from the standard it is customary to write “ stand¬ 
ard connection, except as noted 

The first set of holes from the left-hand end in the web is for the 
connection of an 8-in. beam framed to this beam. Note that 5 T 5 ^ in., 
the spacing horizontally of these holes, and 2\ in., the spacing verti- 






















































206 


STEEL CONSTRUCTION 


cally, are the measurements in the outstanding legs of the standard 
connection for an 8-in. I-beam. 

The next set of holes in web are for the connection of a 4-in. 
beam which frames flush on top with the 8-in. girder; this fixes the 
holes at 2 in. from the top as shown. 

The single hole at the right-hand end is for a standard anchor 
rod. This measurement of 2 in. from the end is a customary meas¬ 
urement on such anchor holes, although some specification may call 
for something different. 

In the flange near the left hand is shown a group of holes; these 
are for the connection of a channel which runs over the top of beam. 
As these holes are not symmetrical with regard to the axis used in 
locating the group, it is necessary to space each set with regard to 
their axis. These holes are spaced symmetrically with respect to 
the web of beam, and the distance between them is the standard 
gauge for punching the flange of an 8-in. beam. Where holes come 
in a flange these standard gauges should always be followed unless 
there are special reasons for not doing so. 

In the drawing, the plan of the bottom flange is given, although 
there are no holes in it. Where printed forms ready for filling in 
measurements and details are used, this would appear and it is added 
here for clearness. In actual details, however, it should not be 
drawn if it involves extra work and if there is no punching or cuts to 
be shown. 

Fig. 197 shows a channel detail which is similar to Fig. 196 
except that it is coped. In such cases, always specify the size and 
weight of beam to which it is coped and give the relation of the tops 
or bottoms, as for instance, “cope to a 12 in., 31^-lb. I-beam flush 
on bottom”, or “cope to a 12-in., 31J-lb. I-beam as shown”. In 
case the beams do not cope flush on top or bottom, the outline of the 
beam to which it copes should be shown in red in the sketch, and 
the relations of flanges clearly indicated. 

Below the sketch in beam details, is always given the specifica¬ 
tion of size and weight of beam or channel and the overall length, 
the number of pieces wanted and the mark to be put on them. This 
specification is used by the mill in entering the order for its rolling 
list and it is important that it agrees with the detailed measurements 
in the sketch. Also if the beam is cut on a bevel the extreme length 




fMBivetsi 
(W Open Ho/esji" 


STEEL CONSTRUCTION 


207 


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208 


STEEL CONSTRUCTION 



Fig. 198. 


I-Girder-3-20-80*-!s.- 38 -8‘long oa Mrer F/vo. Ftooe’/Vo. L 






























































































































STEEL CONSTRUCTION 


209 


of beam required to give the specified bevel should be given. Fig. 
198 shows a beam girder bearing a shelf angle for the support of wind 
joists, or a terra cotta arch of different depth from the beam. This 
requires an additional line of dimensions, giving the rivet spacing 
and the length and position of angles. The maximum rivet pitch 
of six inches is generally used. Where this angle interferes with 
connection holes or separator bolts, as in Fig. 198, it has to be cut, 
and in such cases the rivet pitch must be figured out to agree with the 
measurements fixing the connection holes or separators. 

At the top or bottom of a sheet, such general directions as apply 
to the work as a whole are given, as “Rivets, f in. diam. except 
noted”. “Open holes in. diam., except as noted”. “Paint, one 
coat Superior graphite”. 

The student should carefully study all the dimensions in con¬ 
nection with the cuts, and should thoroughly understand these and 
the problems before starting on the subject of detailing from a plan. 
Note at each side of a beam sketch, are figures preceded by a plus 
or minus sign. These measurements denote the distance from the 
end of the beam in the sketch to the center of the beam or column 
or other member to which it connects, or the distance from face of 
the w T all to end of the beam. These figures are not necessary for the 
complete detailing of the beam, but they are of great assistance in 
checking the drawings, as they show just how much is to be added 
to or substracted from the measurements on the setting plan to give 
the length of piece as detailed. 

PROBLEMS. 

1. Practice making freehand letters of the style shown on the 
details, both capitals and small letters. Make the letters in each 
word of uniform size, also practice making letters of different sizes. 
This is important as it is often necessary on shop drawings to put 
a note on a part of the drawing where space is very limited, and the 
writing must be small. Make a copy of the alphabet (capitals and 
small letters) and a copy of the numerals; also print the following in 
three sizes: 

“All bearing plates to be faced.” 

One size to have a height of T % in. for the small letters, another size 
| in. high, and the third size T \ in. high. 



210 


STEEL CONSTRUCTION 




















































/?// Pii/efs i 
fl/1 Open Ho/es f§ 
Pa/nt One Coat 


STEEL CONSTRUCTION 


211 




Fig. 200 


3-6"-025*Is- 05 above IV7arK First Floor it os. 3, 4, 5* 



















































































212 


STEEL CONSTRUCTION 


2. Make a shop drawing of a 6-in.. I-beam, 6 ft. long, with two 
holes for f-in. rivets in top flange at each end, and 1} in. from the 
ends. Also make holes for f-in. rivets spaced 6 in. apart in the 
middle of the web for the full length. The end holes should be 3 in. 
from the end of the beam. * 

In this example, the only work specified is the punching of the 
rivet holes, and therefore, as no other work is required, the shop 
drawing will consist only of the outlines of the beam, with the rivet 
holes located on the same, and the spacing of the rivets shown by 
dimension lines, as indicated in Fig. 196. 

3. Given a 20-in., 65-lb. I-beam 22 ft long, framed into a 20-in., 
80-lb. I beam. The 20-in., 65-lb. I-beam has a 15-in., 42-lb. I-beam 
framed into each side every 5 ft. 6 in. with its top flush with the 20-in. 
I-beam. If the reaction of each 15-in. I-beam is 7 tons, state the 
number of f-in. rivets required for the connections of the 20-in., 
65-lb. beam and for the connection of the 15-in. beam, using 9,000 
pounds for shear and 18,000 pounds for bearing. 

4. Make a shop detail of the 20-in., 65-lb. beam in the above 
problem, using standard connections. 

DETAILING FROiT FRAMING PLAN. 

The student should now become familiar with detailing from a 
framing or setting plan. Fig. 199 shows such a plan upon which 
is all the information necessary to detail the different members. 
The information given on such a plan is taken from the various 
general plans of the building. This framing is designed for a terra 
cotta arch except the portion having 6-in. beams which is under a 
sidewalk. These beams, therefore, are on a pitch indicated by the 
arrows and the figures .375 which is the pitch in inches per foot. 

The detail of these 6-in. beams is given in Fig. 200. Note that 
at the right-hand end is shown in outline the girder to which they 
frame, to indicate that it copes on a level with this girder. Note 
also that as the web of this girder is vertical while the beams pitch, 
the framing angles have to set on a slope with reference to the axis 
of the 6-in. beam, which slope is given always by a triangle of meas¬ 
urements, one side of which is 12 in., and the other side inches or 
fractions. Never use decimals for this slope on the details as the 
men at the shop are used to working only to inches and the nearest 



STEEL CONSTRUCTION 


213 


sixteenth. On a plan it is well to give the slope in decimals, for if 
it is a fraction over or under a sixteenth, in a long slope some error 
might result in calculating the difference in grades unless the exact 
decimal was used. 

The length of these beams is fixed by the measurement from the 
center of the girder to the face of the wall and the bearing of the beam 
on the wall. This bearing is generally 8 in. or more. The allowable 
pressures on masonry are given in Part I, and by computing the 
reaction on the wall, the proper bearing to give can be determined. 
For the smaller sizes of beams a method would give a result less 
than 8 in., but this should be used in such cases where possible. 

The connection holes for beam No. 5 are on a pitch with refer¬ 
ence to the axis of the beam, since the webs of beams No. 7 and No. 8 
set vertically. 

The tie rod holes are dimensioned on the detail but not on the plan. 
These holes are rarely spaced on the plan, but must be on the details. 
The measurements are such as to follow what is indicated by scale on 
the plan and avoid any other holes or connections such as connections 
for beam No. 7. Tie rod holes should be shown in groups of two, even 
if only one rod bolts to the beam, as in the case of channel No. 2. 

Fig. 201 shows the detail of channel No. 9. This channel re¬ 
ceives the ends of the terra cotta arch along the back and so it is 
necessary to rivet an angle on the bottom for the skewback of the 
arch to rest upon. Note that this stops a little short of each end in 
order to clear the connection angle at one end and the faces of the 
wall at the other. If the connection angle did not interfere, it would 
be well to run this as far as the flange of No. 15, and cut it to give, 
say f in. clearance from this flange. Note the connection holes at 
the left-hand end for a 9-in. channel have a standard connection. 
Where the beam or channel is set before the brick wall is carried up, 
this of course can be done; if the wall is already in, it would be neces¬ 
sary to use an angle on one side only. 

There is 1 in. from the center of the holes for the connections 
to the upper edge of the 3 X 3-in. angles. The connection angles for 
these beams come on the inside of the 16-in. channel and clearance 
for driving the rivet on the back is all that is required here. If the 
beams were framed to the back of channel, this angle would have to 
be tut each side of the connection. 




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fit/ Open Ho/es 
Paint One Coon 


214 


STEEL CONSTRUCTION 




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STEEL CONSTRUCTION 


215 


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216 


STEEL CONSTRUCTION 


Fig. 202 shows the detail of beam No. 11 which frames to beam 
No. 9 at one end, and at the other end comes on a lintel at such a 
grade that the beam cannot be framed to the lintel, and owing to 
the small depth of the lintel, it is not possible to put a shelf angle 
on to receive the end of the 9-in. beam. The most practicable 
way, therefore, is to cut the 9-in. beam and rivet on angles which 
will bear directly on the top of the lintel beams. These angles have 
generally either a 6-in. leg or a 5-in. leg in order to contain sufficient 
rivets to take the reaction of the beam at this end. In this case, 
the cut being small as regards the depth of beam, there is sufficient 
web area along the inside edge of these angles to provide for the shear. 
If the beam had been a deeper one, and the end reaction much 
larger, this might not have been the case. The shear angles would 
then extend back to the uncut portion of the beam far enough 
to provide rivets to carry whole reaction to the angles, and the same 
number of rivets would be required in the portion over the bearing 
area. In general, this construction which is shown by Fig. 136, in 
Part II, should be followed. The holes in the horizontal legs of these 
angles must be spaced to agree with the holes in the flanges of the 
lintel beams, and are determined by the spacing of these beams and 
the standard gauge in the flanges. Note that f-in. rivets are the 
maximum which can be used in the flange of a 7-in. beam, and that 
the holes for tie rods are not in the center of the beam. The posi¬ 
tion of such holes varies; sometimes they are specified to be near 
the bottom of the beam. At other times where different size beams 
are used, as in this case, the spacing is such as to approximate the 
centers of all. 

Fig. 203 shows the detail of the lintel beams to which beam 
No. 11 connects. The table on page 44, Cambria Handbook, gives 
the standard spacing for double beams. These spacings cannot 
always be followed. In this case the beams are spread more so as 
to bring the flanges nearer to the outside faces of the wall which rests 
upon them. Separators are always placed at ends over the bear¬ 
ings and at varying distances, center to center, as noted in Part II. 

Fig. 204 shows the detail of No. 15. Observe the difference in 
details of two ends; one coming on the cast iron column and one on 
the steel column. 




Fit Pixels / 

fl/l Open Hole 5 F Except Holed 
Paint One Coat 


STEEL CONSTRUCTION 


217 



Fig. 203. 


PL/ntel - E-7-/5*is. - 5-O'Long Qtf. Mack /Inst Floor /Los. L3. / S Ship Separate- 














































































All rivets^ 

All open holes H 

Fta.1 nt one coat <^raph ite. 


218 


STEEL CONSTRUCTION 



Fig. 204, 


-15-42*1 15 , -3i , l ? .o.a. Mark 1st Floor’No. 15. 





























































STEEL CONSTRUCTION 


219 


As the beam is a 15-in. beam, while on one side is a 12-in. terra 
cotta arch, it is necessary to provide an angle on this side. The 
bottoms of the 9-in. beams are 3 in. above the bottom of this 15-in. 
girder, and if the connections were central with the 9-in. beams, 
the first hole would be 6J in. from the bottom of the 15-in. beam. 
In order to get clearance between this hole and the upper edge of 
shelf angle sufficient to drive the rivet, and to avoid cutting the 
angle at each connection, the shelf angle is dropped, making the 
upper side of the outstanding leg flush with the bottom of the 12-in. 
beams, and the connection on the 9-in. beams raised \ in. 

Fig. 205 gives the detail of beam No. 12. In this case, the 
length of beam cannot be obtained directly from the framing plan, as 
the beam No. 1 is not perpendicular to beam No. 12. The difference 
in measurement of the ends of No. 1 from the wall line is 1 ft. 10 in., 
and the length parallel to this wall and square with beam No. 12 is 
12 ft. 8 in. from the center of the column. As No. 12 is 4 ft. 2J in. 
from the center of the column, the bevel from the column to No. 12 is 
4.21 

—-— X 22 = 7.31 inches, or 7A in., to the nearest sixteenth. 

12.67 

The length of No. 12 from the face of wall to center of No. 1 
on this line, therefore, is 14 ft. 10j-J in. The bearing on wall being 
8 in., and the clearance at the other end \ in., the total length of 
beam is 15 ft. 6 r \ in. 

The girder No. 1 coming under the sidewalk is 4 in. lower than 
beam No. 12. This is not enough to get a shelf angle on the girder, 
or to get angles over the top of the girder, as in the case of beam 
No. 11. It is necessary, therefore, to drop the connection on No. 12 
and notch the beam over the top flange of No. 1. This notching is 
not figured on as reducing the required number of rivets in the con¬ 
nection, but does give an added element of strength and of stiff¬ 
ness. In order to get the connection in, it is necessary to go within 
1 in. of the bottom flange of No. 12 and the top flange of No. 1; thus 
encroaching somewhat on the fillet in each case. As the required 
number of rivets can not be obtained in two lines, as is generally the 
case, it is necessary to use special spacing as shown. The connection 
specifies bent plates rather than angles; where the bevel is over 1 in. 
to the foot, it is customary to use plates. 




220 


STEEL CONSTRUCTION 


h 

Ir^l 

oo 



l-li.-dl.S-I IS-6^' !<jr. o.a. Mark "1st Floor'No /£. 













































































fill Pii/ets i 

fill Open Holes {§' 

Paint One Coat 


STEEL CONSTRUCTION 


221 



/-9-/3.F5-F 4-/p Long a a Mark First F/oor /Vo./7 











































































222 


STEEL CONSTRUCTION 


Schedule of T/e Pods 


NO. of 

PIECES 

LENGTH-'L' 

MZJPK 

FEET 

INCHES 

3 

3 

Si 

F/PST FLO OP 

4 

4 

5/ 

* 

/ 

4 

"J 

- 


Schedule of Field Bolts 
for F/pst Flood 


Fig. 206 gives the detail of channel No. 17. This channel has 
a single angle framing. This is a case Where the channel comes into 
a wall so that a connection angle on the back side cannot be reached. 
In order to get the necessary number of rivets in the outstanding leg, 
therefore, a 6 X 6-in. angle must be used. The holes at the left- 
hand end in the web are for the connection of a channel similar to 
what is shown in the end view. 

These holes are located 
■ ■ ■ from a line which in turn 

^ _W is located from the end of 

the channel; this axis’ is 
the back of the channel 
framing in. 

Fig. 207 gives a schedule 
of tie rods and of field 
bolts, and of bearing plates 
for the framing as shown on 
Fig. 199. 

Note the over-all lengths 
of the tie rods is 3 in. longer 
than the length, center to 
center of beams. This al¬ 
lows lj in. for the two 
nuts, about f in. for half 
the thickness of the two 
webs and about in. pro¬ 
jection of rod beyond the 
Fig. 207. nut. 

The length of field bolts 
is always given from the underside of the head to the end of the bolts. 
The grip is the thickness of the metal between the underside of the 
head and the nut; that is, the thickness of the connection angles and the 
web. A projection of J in. or | in. beyond nut should be allowed for. 

Fig. 208 shows the setting plan of another floor, a part of which 
the student will be required to detail as problems. 

Fig. 209 shows the detail of the beam girders, Nos. 2 and 3. 
As the beams are spaced close together, connections can be used only 
on the outside of the webs. The same number of rivets in the out- 


NO. of 

PIECES 

SIZE 

LENGTH 

FEET 

/ms* 

£9 

i 

0 

ti 

47 

/ 

O 

a 

4 

$ 

O 

/ir 


•SCHEDULE OF Be APING PLATES 
F«r F/esr Flood 


NO. of 

P/ECES 

5/ZE 

LENGTH 

FEET 

INCHES 

5 

Q*i' 

O 

8 

6 

8 m *r 

/ 

O 












































STEEL CONSTRUCTION 


223 


standing legs must, of course, be used, as would be required for a 
double-angle connection, and more rivets must be used through the 
web, as these are in single shear instead of bearing or double shear. 
In the case of the beams shown, seven rivets are all that are necessary, 
although the standard connection requires eight. 

In such a connection as girder No. 2 to girder No. 1, it is neces¬ 
sary to use bolts, as there is no way of riveting. In the case of the 
connections of beams to girders Nos. 2 and 3, rivets might be used 



Grades given are distances of bottoms 
of beams bet on finished f/oor Line. 


Fig. 208. 

by separating the two beams forming each girder and sliding the 
framing of each outside bay over on the wall far enough to get in 
between the beams of girders to hold the rivets. After all the beams 
had been riveted up, the whole frame could then be moved back into 
position, and the girders bolted up. Such an operation would be 
expensive, as it would require considerable extra moving of the beams. 
In general, bolts through webs of both beams would be used. If the 
connection was very heavy or the greatest possible number of bolts 
barely sufficient for the load, turned bolts should be used. In this 


















































224 


STEEL CONSTRUCTION 



Fig. 209. 


2. Girders each 15-G5*Is. 24~!!%■ f^.o.a Mn.Gm fL.flos.Z.3. 






































































































STEEL CONSTRUCTION 


225 


case, the holes should be punched ln - smaller than the diameter 
of the rivet, and then reamed to a diameter in. larger than the rivet 
so as to remove all ragged edges; the bolts would be turned down to a 
true diameter, the exact size of holes, for their whole length*. 

Fig. 198 shows the detail of girder No. 1. This girder receives 
a terra cotta arch on each side and as the girder beams are deeper 
than the floor beams, angles must be used to receive the arch. These 
angles have to be cut to clear the connection angles on the beams 
framing in, however. The separators must be spaced so as not to 
interfere with the rivets in the shelf angles. 

The student should carefully study every detail shown in the 
preceding cuts, and should thoroughly understand every feature of 
them and every note, and the reason for all the special features ap¬ 
pearing in them. He should work out for himself all the measure¬ 
ments given by the details so that he will understand these and know 
just how to proceed in other cases. 

PROBLEMS. 

1. Make a shop detail of a 10-in., 25-lb. beam, 12 ft. long, 
resting 8 in. on a brick wall at each end and having holes for anchors 
at each end, and holes for tie rods in the center. 

2. Make a shop detail of a 12-in., 40-lb. beam, 15 ft. long, 
framing into a 15-in., 42-lb. beam flush on bottom at one end and 
into an 18-in., 55-lb. beam 1 in. below the top at the other end. The 
12-in. beam has holes for three 8-in., 18-lb. beams with standard 
connections spaced equally throughout the length, center to center, 
between girders. 

3. Make a shop detail of a 9-in., 21-lb. beam with a 4 X 3 X |- 
in. angle riveted to the beam the full length. This angle to be placed 
with the horizontal leg down and as near the bottom of the 9-in. beam 
as possible, and the 4-in. leg to be out. The beam rests on a wall 
8 in. at each end and it is 13 ft. 9 in. between walls. 

4. Make a detail covering channels No. 7 and No. 8, shown in 
Fig. 199. 

5. Make a detail of channel No. 17 in Fig. 199. 

6. Make a detail of channel No. 10 in Fig. 199. 

7. Make details covering the 5 to 8-in. beams, and the 14 to 
17-in. beams in Fig. 208. 




226 


STEEL CONSTKUCTION 


COLUMN DETAILS. 

There are five main features in the detailing of a column. 

1. The base or foot of the.column. 

2. The shaft or the line members composing the column. 

3. The cap or top of the column. 

4. The connections for other members to the column. 

5. The bill of material required to make up the completed 
column. 

A column detail is of necessity more complicated than a beam 
detail and may at first appear so confused as to be unintelligible. 
If the student will bear in mind, however, these five features and take 
each by itself, it will soon become clear. 

Details of Base. The character of the base or foot of the 
column depends upon what it rests. If this is the first section of the 
column, it will generally rest on a cast iron ribbed base, or a plain 
steel or cast iron plate. It is the duty of the designer and not of the 
draftsman to determine which one of these will be used. 

Fig. 224 shows a detail of a foot of a column resting on a cast 
iron ribbed base. The base is always designed so as to take the load 
of the column by direct bearing between the line members and the 
top of the base, and the angles which are riveted to the column are 
intended simply to hold it in position in the base. 

If a plain cast iron plate is used, a connection similar to the 
above would generally be used, because in this case the load would 
be light and the plate thick enough to withstand the upward pressure 
without spreading the foot of the column. Such plates must be cal¬ 
culated in the same way explained for bearing plates under beams. 
See Part II, page 96. The projection of the plate beyond the shaft 
is exposed to bending just as the plate under a beam is where it pro¬ 
jects beyond the flange. 

If a steel base plate is used, this is generally riveted to the col¬ 
umn and the load then must be spread out beyond the lines of the 
shaft by vertical plates or angles, called shear plates or angles, so 
as to avoid an excessive bending moment. The size and shape of 
this plate are determined by the area required to properly distribute 
the load on the masonry and the direction in which the foot can be 
most readily spread by means of the shear plates and angles. The 



STEEL CONSTRUCTION 


227 


thickness of the plate is determined by the same formula as before 
used for cast iron and bearing plates; generally it is J or 1 in. thick. 
The projection is the distance beyond the edge of the shear plate, 
or the outstanding leg of the shear angle. 

The number of rivets between the column and the shear plate 
or angle is determined by considering the area exposed to bending, 
as the outer edges of the base plate and of the shear plate. The load 
being uniformly distributed, the pressure per square inch is the total 
load divided by the total area of the base plate, and the load on 
rivets in the shear plate, therefore, is this unit pressure multiplied 
by the area over which the shear plate distributes it, as above stated. 
The balance of the column load may be considered as distributed by 
direct bearing of the line members on the plate. 

It is generally not necessary to use more than six rivets in one 
line for connection of shear plates, and some system of plates and 
shear angles should be used so as not to exceed this number, or if 
this is not possible, a cast iron ribbed base, or a smaller steel plate 
bearing on steel beams should be used. The exact number of rivets 
determined as above may be decreased somewhat if this exceeds six, as 
the plate, even if not supported by the angles or shear plate, is capable 
of taking some of the load before bending would result. Judgment 
determines largely how much consideration can be given to this factor. 

If the column is an upper section, and rests on the top of another . 
section, the foot is then generally of a character similar to what is 
shown in Fig. 214. It is, of course, essential that the holes in the 
foot should match the holes previously detailed in the cap of the lower 
section. Where a horizontal splice plate is used, this should be large 
enough to bear over all the line members. Where the column be¬ 
low is of greater dimension, the fillers must be shipped bolted to the 
foot of the column. 

Cap Details. These are of the general form shown in Figs. 
211 and 214. They will vary somewhat according to the sections 
composing the column. In high buildings it is essential to have 
vertical splice plates to give the necessary stiffness to the joint. Usu¬ 
ally this splice plate extends far enough up to take three lines of 
rivets. The ends of the columns are always faced to true plates at 
right angles with the axis of the column, and so the splice plate is not 
designed to transmit any of the vertical load. 



228 


STEEL CONSTRUCTION 


In arranging the holes in the cap, it is necessary to consider 
the section which comes above so as to space these holes to conform 
to what may be feasible in the foot of the upper section. This other 
section may be of smaller dimensions, and it may then be necessary 
to space the holes in the lower section closer, so as to make it possible 
to rivet up without interfering with the line members, or coming too 
near the edge of the connection angle. 

Shaft Details. This consists in locating all shelf and bracket 
angles and connection holes, or other special connections, and in 
spacing the rivets so as to conform to these connections, and not to 
exceed the maximum or minimum distance. 

The rivets in shelves and brackets having been spaced, and the 
position of these on the shaft from the top and bottom having been 
fixed, it only remains to divide the space into as many equal rivet 
spaces as possible, and put the odd spaces near the top or bottom of 
the shaft. 

Six inches is the maximum pitch allowed, and if the metal 
through which the rivet goes is less than | in. thick, the maximum 
pitch is sixteen times this thickness. Three times the diameter of 
the rivet is the minimujn pitch which’can be used. 

Illustrations of Column Details. In making column de¬ 
tails, the views are not complete views, regarded as mechanical 
drawings. The essential feature is clearness and, as the drawing 
must of necessity show as many details, it is important to omit what 
is not necessary. For instance, a column which is made up of four 
angles and a web plate should show, to be complete, the dotted lines 
indicating the legs of the angles riveted to the web. It adds to the 
clearness, however, to omit these where a connection comes on the 
flange. Similarly, in showing a view of the flange, it will add to the 
clearness to omit showing the connection angles which rivet to the 
web and are sometimes indicated back of the flange by dotted lines. 

In the case of the web view, it is generally necessary to show 
what is on both sides of the web, as except in special cases, one 
elevation only of the web is given. 

Fig. 210 gives the detail of the cast iron column shown on the 
setting plan in Fig. 199. The foot of the column rests on a solid 
cast iron plate and sets into a ring on this plate to prevent lateral 
movement. There are a variety of details for holding the foot of 






9 : 7 


STEEL CONSTRUCTION 


229 


















































































































230 


STEEL CONSTRUCTION 


the column in place, but this is one very generally used. The rela¬ 
tion of the bottom of the base plate to the finished floor line should 
always be given to enable the plate to be set at the proper grade. 

Connection of beams to columns is by a shelf under the beam 
and a lug bolted to the web to hold the beam in position. The top 
surface of the bracket should slope about T V in. so as to avoid the 
tendency of the beam when it deflects to bring the load on the outer 
edge of the bracket. 

The lugs are generally J or j in. thick. The bracket should 
of course be wide enough to receive the flange of the beam. The 
thickness of the bracket and rib under it varies with the load. This 

rib in general is beveled at an 
angle of 30 degrees with the axis 
of the column. The accompany¬ 
ing table gives the thicknesses 
which are sufficient for most 
cases. 

The lugs are braced by ribs 
back to vhe* column shaft so as 
to prevent being broken off. 
The flange at the top which 
connects the two sections of the 
columns may be J in. or more, up 
to 1J in. in some cases; for usual 
sizes of columns, f or 1 in. is 
sufficient. The holes in the 
flange must be spaced so as to 
enable bolts to be turned up 
without interfering with the shaft 
of the* column and the distance 
from the top of the beam to underside of the flange must be sufficient 
for this purpose. 

Fig. 211 gives the details of the beam connections, and the cap 
for column No. 2 in Fig. 199. This is not a complete shop detail 
but shows one of the steps in the complete detailing of a column 
which is generally the first step; namely, the drawing of connections, 
locating the same on the shaft and spacing rivets in the connections. 


4\ L _A 




/ 

k 


Size-ofEk/m 

-b- 

-t- 

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Up to 7" 

4" 

4 

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sf 

r 

r 

XT 

g 

/f 

6" 

&ar 

6f 

/f 

a" 

24" 

7f 

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Dimensions of Brackets and Lugs. 


























STEEL CONSTRUCTION 


231 


,2 &>&' 



COLUMN mC 

Showing Connections 
for F/oor Beams 


ITEM 

KIND 

ft 

8fxfPt 

3 

3i'x3’xfL s 


U’xCxf'ls 

D.-OM 

6x6 xfl*. 

E 


F 

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L 

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Fig 211. 






































































































































































232 


STEEL CONSTRUCTION 



Fig. 212. 














































































































STEEL CONSTRUCTION 


233 


Note that the spacing for holes in the cap and in the shelf angles 
is given in a separate plan, and in this plan the holes are located 
with respect to each angle and are also located by measurement 
between holes on opposite sides of the axis of the column. This 
is advisable in case there is any variation in the measurement back 
to back of the column angles, or between outside faces of angles. 
After the column is riveted up, other measurements can be adjusted 
to the over-all measurements between holes; this measurement is 
also useful in checking. 

The cap angles are bolted on for shipment. In many cases 
it would be impossible to place a beam between the webs of two 
columns without taking off the cap angles; for this reason, cap angles 
on the web should always be shipped bolted on. Cap angles on the 
flange, in many cases, do not require to be bolted on. Where there 
are flange plates, the rivets must either be flattened or the beam 
cut short to allow clearance for the rivet heads. Where the spacing 
between the vertical lines of rivets in the flange is sufficient to allow 
the flange of the beam to be lowered between them, the cap angles 
could be bolted on and the rivets would not then need to be flattened. 

The draftsman should constantly have clearly in mind what is 
necessary to enable the structure to be erected. The details must 
often be modified in some way to avoid a construction in which it is 
impossible to erect some member. 

The outstanding legs of shear angles under the brackets are 
here shown riveted together. As previously stated, many details 
are made with only one shear angle, and where two are used they are 
not always riveted together. For ordinary loads it is not essential 
to rivet them together, but is better construction and should always 
be done where the loads are very considerable. 

Fig. 212 shows the detail of a column composed of two angles, 
back to back, and Fig. 213 gives the bill of material. The only 
loads in this case are from the beams over the top. If a beam was 
framed into the shaft of the column parallel with the axis of the 
two adjacent legs, a connection of a plate riveted to these angles 
with shelf angles riveted to this plate similar to what is shown for 
the head, could have been used. The student should study care¬ 
fully the bill of material of this column, and thoroughly understand 
each item and the notes regarding the shop work to be done. 






234 


STEEL CONSTRUCTION 


Fig. 214 shows the second section of a box column made of two 
channels with flange plates. Table V, Part I, gives the distance 
back to back of channels, in order that the radius of gyration shall 
be equal about*each axis. In a box column the distance back to 
back of channels, should never be less than this. The Carnegie 
Company and most other shops have standard spacings for such 
columns which should in general be followed. 

As the flange plates on this section are not as thick as those on 


Bill ofMateria! Bor 4 Columns. 


mn 

o/ 

PIECES 

kind 

SIZE 

LENGTH 

WOPK 

FEET 

//KCHES 


8 

ANGLES 

4*4'*E 

9 

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Fig. 216. 


Fig. 215. 


the lower section, it is necessary to ship filler plates bolted to the 
column. 

There are two beams framed to each flange of this column so 
that the shear angles are spread to come as nearly as practicable 
under the web of the beams. These angles cannot always be made 
to come directly under the web on account of the relation between 
the spacing of beams and the spacing of rivets through flanges of 












































































































































































































































































































































































































































































































































































































































STEEL CONSTRUCTION 


235 


channels of columns. Some variation in size of angles can be made, 
however, at times to effect this result. 

Where box columns are used, it is better to keep the spacing 
back to back of channel the same throughout all sections. If this 
is less in the upper sections, it brings the load of this section on to the 
horizontal splice plate between the sections. The distance between 
the cap and shelf angles is generally J in. more than the depth of the 
beam, to allow for clearance. The rivets between the cap and shelf 
angles are flattened here, as with one beam in position there would 
not be space to lower the other beam between the rivet heads. 

Fig. 215 gives the bill of material for these box columns. Fig. 
216 shows the framing of the beams coming on columns No. 1 and 
No. 2. detailed in Fig. 217. This column has a heavy steel base 
riveted to it. The load on the section is 265,000 pounds and it will 
be seen therefore that the rivets in the shear plates are amply suffi¬ 
cient for the portion of the load coming upon them. The plate W 
riveted to the web increases the bearing area of the foot of the column 
and adds somewhat to the efficiency of the base. 

In this connection and in such cases where shear angles are 
used over a shelf angle involving the use of a filler, below the shelf 
angle and back of the shear angles, as shown by the details of this 
column, the student should note the difference between a tight and 
a loose filler. 

Fillers G and R are loose fillers. They have no rivets holding 
them individually to the main members. The stress in the rivets 
through such a filler does not go into the filler, as there are no extra 
rivets to take it out again from the filler to the main members. Such 
rivets, therefore, are subject to bending if calculated for their full 
value. They should not be considered for more than one-half the 
value of rivets directly connecting the main members. Filler W is a 
tight filler as regards the two rivets through the angles X on the axis 
of the column. A tight filler has provision by additional rivets for 
taking the same amount of stress from itself to the main member as it 
receives. 

The open holes shown in the base plate are for anchoring to 
the footing—such heavy columns are not usually anchored except 
in special cases; it is well, however, to provide for this if there is any 
possibility of its being required. 



STEEL CONSTRUCTION 


2bfc 


Bill of Materia/ for 2 Co.turnns 


ITEM 

NO. of 

PIECE 

KIND 

S/ZE 

LETLGTH 

W02K 

FEET 

INCHES 


2 

WEB PL5. 

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24 

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24 

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4 

FFGLES 

6"*4"*f 

o * 

/of 


Y 

4 

F/LLEPS 

5'*£ 

a 

//l 


Z 

2 

BEST PLS. 

2T*tf 

2 

o 

COFNTEESL/NK 


6 

BOLTS 

3" 

a 

0 

3i 



/2 

" 

3* 

4 

O 

3 



?0 

// 

r 

0 

2 



Fig. 218 . 











































FIG. 217. 















































































































































































































































































































































































































































































































































































































































































































































STEEL CONSTRUCTION 


237 


In the connection for floor beams it will be noted that a 10-in. 
beam comes in on one side of the web and a 12-in. beam on the other 
side. Such cases often result in special cap angle details in order 
to provide for riveting without interference on either side. In this 
case it is impossible to get the upper holes in cap H more than 7 in. 
from the upper edge of cap INI unless these holes are brought nearer 
the upper edge of H than 1J in., which it is undesirable to do. It is 
necessary, therefore, to add an extra filler B B to fill out flush with 
the angle N so as to be able to rivet. The student should follow the 
detail through and see just why this condition results from the meas¬ 
urements given. 

The four rivets in angles L are countersunk on the fa^ side so as 
to avoid a filler and riveting through angle N. 

o O o 


/Veufra/ 


Axis 


The 10-in. beam connecting on the flange of the column at one 
side of the axis, requires a connection 
similar to that shown. If the load com¬ 
ing off the axis was very heavy, a deeper 
shear plate would be used back of the 
shelf angle, and it would be better to 
run this shear plate across both angles 
of the flange, both to provide for the 
bending on the rivets and also to distri¬ 
bute the load more uniformly with respect to the axis of the column. 

There are no standard details for eccentric and special framings. 


Fin-. 222. 


The draftsman must use his judgment and endeavor to get as simple 
and effective connections as possible. 

The section which comes on top of this one has 5-in. angles, 
in order to use standard spacing in these angles, therefore, the spac¬ 
ing in splice plates has to be on a special gauge and this place is 
beveled to give a neater appearance when the two sections are riveted 
together. Fig. 218 gives the bill of material. 


Fig. 219 gives the detail of an angle over an opening resting 
in a wall at one end and framing to a beam at the other. The holes 
in the horizontal leg* are for securing the frame of the window. As 
this angle has framing on one end only it is not reversible and there¬ 
fore for the wall on opposite side of the building the angle must be 
made “opposite hand” or reversed. 












238 


STEEL CONSTRUCTION 


fill Pii/ets?' 

All Open Holes H' 
Paint One Coat. 


4-z 


3 : 6j" 




ef zi' 


7-ef 

4" 

65paces & /-<?» 7-0 




C 


,• rr* 4 

4 



u- 

- 

T 


I 

CxJ 


COtV/Y 

2L5-6 x4*/a’ 
0-3"L$ 


I 


2f 


’z£ 


/-6x4xf-P L/ke Th/s - 7-8j Long a a. /V/nPK "Bo/lep Poom*Ho./Z 
J~6xflxfL-P eixejpse -7-6J'Long act. Mxtpn Bo/lep Boom" f/o. /9. 

Fig. 210. 



Fig. 221. 






















































































































WTp 









































































































































































































































































































































































































































































£:/ 
































































































































































































































































































































































































































































































STEEL CONSTRUCTION 


239 


















































































































240 


STEEL CONSTRUCTION 


Fig. 220 gives the detail of a spandrel girder and shows in out¬ 
line the relation of the stone facing to the girder. This wall section 
is a pier and the width of it is indicated by the length of the 8-in. 
channel at the right-hand end. At the opposite end the wall is only a 
covering for the column and is carried on the column. This channel 
supports the block surrounding it, which in turn supports the mass 
of stone above; the course below is hung by anchors, to the 8-in. chan¬ 
nel. The channel is supported by brackets from the beams which 
are detailed separately for clearness, although they are shipped 
riveted to the beam. The connection A runs back to the column. 
There are two floor beams framed to the girder, but as the space 
between center of beams is 11 in. there is sufficient room to drive 
rivets passing through only one beam, and this is preferable, there¬ 
fore, to using through bolts. 

Note the specification “Ship UnassembledThis means that 
the two beams are not bolted together for shipment. 

Fig. 221 gives the detail of a cast iron base for a plate and angle 
column having a 12-in. web. The outlines of the members of the 
column shaft should be carried down by similar outlines in the cast 
iron base. In this case the box of the base is H-shaped and the 
centers correspond to the centers of the shaft members. The thick¬ 
ness of this box under the column must be sufficient to carry the 
whole load of the column without exceeding the safe compressive 
strength of cast iron. The size of the base depends upon the area 
required to distribute the load on the footing. The purpose of the 
ribs and base is to resist the tendency to break, due to this uniformly 
distributed load on the footing. Failure would generally occur 
through the bending action of the portion of the base projecting 
beyond the box. The moment on this may be figured as for a beam 
fixed at one end and free at the other and loaded uniformly with the 
load per unit of bearing surface. 

Taking one rib and the base half way on each side between the 
next rib would give a section at the box, which may be taken as the 
fixed end, similar to Fig. 222. Calculate then the position of the 
neutral axis and figure the moment of inertia of the section about 
this axis. Having determined the bending moment for the width 
between the ribs, the fiber stress in tension and compression can be 


\ 



STEEL CONSTRUCTION 


211 


found by the formulas used in calculation of beams. 


' = i 


where 


M is the bending moment in inch pounds, y the distance from the 
neutral axis to the extreme fiber, and I the amount of inertia. 

A section must of course be assumed at the outset and it may be 
necessary to modify this to come within the requirements. It is 
necessary also to calculate the stresses at the most unfavorable sec¬ 
tion, and to see that there is sufficient metal across the corners to 
prevent Cracking diagonally between the foot of the ribs on adjacent 
sides. 

Different sections of cplumns require, as previously stated, 
different sections of box under the column, and this would affect 
the arrangement of the ribs more or less. These ribs in general 
should be at an angle of 45 or GO degrees. In some cases lower bases 
can be used, but these are of course subject to greater bending strains. 


PROBLEITS. 

1. Given a 12-in., 31 J-lb. beam framed to a column at each end, 
the distance between faces being 12 ft. 21 in. The beam has two 
7-in., 15-lb. I-beams framed on one side and opposite these in each 
case is a 12-in., 31 J-lb. I-beam. The distance from center of con¬ 
nections to the face of the column at each end is 3 ft. 52 in. Make 
a shop detail of the 12-in. girder, all beams being flush on top. 

2. In the above problem, if the 7-in. beams frame at the other 
end to a 12-in., 311-lb. beam along a wall, both being flush on top. 
and it is 11 ft. center to center of girders, make shop details covering 
both 7-in. beams. 

3. Given a 15-in., 33-lb. channel framed to a column at each 
end, the distance being 1G ft. 5J in. between faces, and the channel 
having a 31 X 2\ X J-in. angle on the back side, with the long leg 
vertical and 1 in. from the bottom. A 10-in., 25-lb. beam frames 
flush with bottom of the channel 5 ft. 4} in. from face of each column. 
Make detail of above. 

flill Building Columns. Fig. 223 gives the detail of the 
columns shown in Fig. 186, Part II, and by the plate on the preceding 
page. This is a latticed channel column. Each flange is double 
laced, that is, it has two systems of lattice bars. In many cases such 
columns have only one system across each flange; in such cases the 


I 




242 


STEEL CONSTRUCTION 



Fig. 225. 


Sing/e Lacing' 

/-Bppce-B- 8-HZ5-[s-LflCED- Il'-lfLONO OAMMK No. I 





































































































STEEL CONSTRUCTION 


243 


bars on one flange would,cross those on the opposite flange; just as 
if one system shown by Fig. 186 was on one flange and the other 
on the other flange. 

O 



This column has a bracket for a crane track girder with a dia¬ 
phragm bracing the crane girder to the column. The roof column, 
as shown by Fig. 186, is a plate and angle column and sets down 


4A6xJj 


Z2rf 


s-/oF V 

s-/oF ^ 


5 

&F2&5* 

AfkPM 




s'-n’ 

. s'-tf 

6-/0’ h 


* 

% 

% 


/m/>, 


Basement Framing 

Fig. 227. 


between the channels, as the web runs at right angles to the web of 
the channels. It is always better to avoid re-entrant angles in a 
plate if possible. In a case like this where a bracket plate comes into 
the lines of the column at the top and there is a plate the width of the 





















































211 


STEEL CONSTRUCTION 


flanges above this point, it is better to make this a separate plate. 
If this plate is necessary for the effective area of the column the joint 



can be faced. The bracket and shelf angles on the plate are for a 
beam framed between columns. 


-ffoofp/fc/?-JS 


1 — 




//- 

o' 






IS 1 . 

¥ 


* 




rz 








8: 

78 

tt 




y 

to 


-d 

y* 

fro 

iff 

nCt 

‘p 






K3? 

/5c 

rz 

nCt 




-U 

•nte 

rs 

* 

nte> 

'S 




-/I// beam? ore //vs/? or? top- 
-/!// 7* /&//?(/ /o //oofSeams- 

Fig. 232. 

The student should be able to follow this detail and understand 
all the points without further explanation. 









































































I 












































































































































































































































































































































































































































































































STEEL CONSTRUCTION 


246 


Fig. 224 shows another type of column made of a web plate and 
four angles with channels across the flange angles, the flanges being 
turned in. 

There are various reasons for turning the channels with flanges 
in; here it is desirable to have a 10-in. arch for stiffness, and the thick¬ 
ness of the wall in which this column comes makes it necessary to 
turn the flanges in; this also allows the column to set flush with the 
inside face of the wall and gives a smooth surface. Then again, 
this gives good connection for the cranes girder bracket and for 
the wind strut below, at N and O. - 

The top of this column receives a heavy floor girder and another 
column; the latter column is made of a smaller web so as to provide 
a seat over the main column members for the girder. Fig. 225 gives 
a detail of the wind strut which frames between the columns. 

In columns of the type shown in Fig. 224, the dimensions must 
be such as to give room between the flanges of channels, and between 
the flanges and web, to rivet up the different members. 

For light building construction columns are sometimes made of 
hollow iron pipe fitted with a cast iron cap and base. The dimen¬ 
sions, weights, etc., of standard steam, gas, and water pipe, as manu¬ 
factured by the American Tube and Iron Co., will be found on page 
344, Cambria Handbook. Fig. 233 gives a diagram giving the 
“strength of wrought iron pipe in compression” according to the 
formula 

10750 - 399 T 
r 

in which L = length of column in feet 
r == least radius of gyration. 

For example, suppose we wish to select a size of pipe suitable 
for supporting a load of 25,000 pounds, and having a length (or 
height) of fifteen feet. Along the left hand side of the diagram, 
under “thousands of pounds” find 25 (i.e. 25 thousands), and then 
find the length ( = 15 feet) along bottom line of the diagram. Fol¬ 
low the vertical line at 15 feet until it intersects the horizontal line 
through 25 thousands, and the nearest inclined line above that point 
will give the diameter of the pipe to be used. In this case a 5-in. 
diameter will be required. 



246 



STEEL CONSTRUCTION 

- 



Fig. 234. 



Fig. 235. 


























































































STEEL CONSTRUCTION 


247 


Approx. Weight of Steel In Bulletin gs -per Sg. ft. a rea 
covered for use in determining dead load 

L engtr 

n 

Span 

or 

Roof 

Distance 

between 

Trusses 

Height 

Pitch 

Of 

Roof 

Load 

on 

Roof 

Walls 
to be 
of 

Weighti/b. )perSg. Foot of — 

Remarks 

OT 

Building 

i u 

Eaves 

Trusses 

Column 

Purlins 

Frorng 

Cor.J 

Total. 

49-3" 

In Z Spa'll 

98-5 

16-5 

19-9 

// 

& 

30 lb. 

Cor.I 

238 

2.9 3 

2.10 

422 

4.90 

16.78 

Trau Crane inhalf 

the buildino 6 T. 

1 tt 

112. 6 

86'-6' 

ia'-6 

26-3 

6" 

30- 


207 

150- 

227 

227 

3.72 

11.87 


84-0 

48-6 

12-6' 

20-0" 

6" 

35 " 

Brick cur¬ 
tain walls 






16.00 


70-0 

Jn 2 Spans 

720-0 ' 

17-6 

40-6 

6" 

30 <• 

If 

1.57 

3.15 

1.70 

343 

1.68 

14.40 

Trau. Crane in half 

the build in a 15 Ton. 

50-0 

42-0 

12'-6 

18'-6’ 

6" 

40 n 

Cor-Iron 

1.77 

1.36 

1.93 

5.01 

5.58 

15.65 

Ordinary 

50-6 

42-0 

16'-8 

18-6 

6" 

30 « 

II •• 

1.57 

145 

2.83 

480 

5.58 

16.33 

If 

120-6 

50-6 

17-0" 


6" 

55... 

Brick 

33? 


3.15 

0.72 

2.50 

9.69 

M Y. Bfo Laws 

372-6 

In 2 Span* 

//5r0" 

19-6' 

21-6 

4" 


/ 9 

4.81 

0.67 

2.65 

0.67 


8.80 

Plans made by 

B- and 4. R H. 

725-6 

58-6 

!2 - 6' 


6" 

40" 


4.52 



0.80 


5.32 

1600lb.onbot. ch- 

S 8-0" 

796-9 

OneSpan 

82-0 " 

16-42. 

12'- 7" 

4 " 

30 

Cor.-I 

4.05 

0.86 

2.08 

1,81 

3.00 

11.80 

Ordinary Export. 

59-/' 

40-/6 

tl-'3 u 


6" 

Plans 

Furmshec 

Brick 

3.43 


3.78 

1.59 


8.80 


56-0’ 

29-6 

!7'-2z 

25'-6' 

6 " 

40 lb. 

Brick cur¬ 
tain woHs 

1.84 

3.08 

2.38 

245 

2.65 

12.40 



Fig. 236. 



Fig. 237. 

o 






































































































































































218 


STEEL CONSTRUCTION 


Ui_L JH . Columns- safe Joads by formula J3750-577^-Square 

Ends. 4-Id laced. {/2"b.to b) tong legs out. Medium Steel- Standard Angles 
Dotted tine js hows limit for 45 diam. Full line for 70 dfam. 

S/jeofAag's 

Area 
4 L s 
Sq.in 

Weight 

perft. 

4/2. 

r 

Safe Loadijb)forLengths In Feet af— 

J2 

13 

14- 

15 

16 

17 

/8 

IS 

20 

2/ 

P X S^Xti; 

3.24 

11.2 

1.28 

■ 27000 

25530 

24050 

22580 

21110 

19640 

18170 

16700 

15220 

13750 

p"x?S*£ 

4.24 

14.8 

1.29 

35700 

33800 

31900 

30000 

28100 

26200 

24300 

22400 

20500 

18600 

2 fx3" x£" 

5.24 

18.0 

1.50 

4780C 

! 458CC 

43 750 

41730 

39 7!0 

37700 

35670 

33650 

3/620 

'29600 

2fx3"x£ 

648 

22.0 

1.50 

59300 

; 56820 

54340 

51860 

49390 

469/0 

44430 

41950 

39480 

31000 

zfx 

5.76 

19.6 

1.76 

56300 

54440 

52590 

\ SO 730 

48880 

47020 

45170 

433/0 

41450 

39600 

2i X3iX/| 

7.12 

244 

1.76 

69800 

67490 

65177 

| 62870 

60555 

58250 

55930 

53620 

5/3/0 

49000 

Zfx3fxf 

8.44 

28.8 

1.77 

83700 

80840 

7798C 

i 75730 

72300 

69400 

66600 

63700 

60900 

58000 

3" X 3fx£ 

7.72 

26.4 

7.7! 

74800 

72200 

69660 

i 67100 

64500 

6/960 

59400 

56830 

54270 

5/70C 

3" X3j>"x§ 

9.20 

31.2 

1.7/ 

89200 

86160 

83000 

! 7S960 

76900 

73800 

70700 

67600 

64500 

6/500 

3" X 4"xfs 

836 

23.4 

1.97 

85200 

82800 

80380 

73000 

75550 

73/40 

70730 

68320 

659/0 

63500 

3" X 4 xf" 

9.92 

34.0 

t. 98 

10/000 

98030 

95/00 

92360 

89600 

86750 

83930 

81/20 

78310 

75500 

3" X 5"xf 6 

9.60 

32.8 

2.52 

105500 

103300 

101100 

98900 

96740 

94550 

92360 

90180 

88000 

85800 

3" X 5”xf 

11.44 

39.2 

2.52 

125800 

123260 

120600 

118000 

1/5400 

1/2850 

1/0260 

/07670 

/05080 

102500 


Fig. 238. 



Fig. 239, 



























































































STEEL CONSTRUCTION 


249 


PROBLEMS. 

1. Fig. 226 shows a framing plan on which is all the informa¬ 
tion necessary to detail the different members. Make a detail of 
column No. 4, assuming that the bottom of the column rests on a 
cast iron web base 12 ft. below the top of the 15-in. beam No. 9, and 
that the column is arranged to receive another column of the same 
size, the joint being 1 ft. 6 in. above the top of the 15-in. beam. 

2. Make details covering the 10 to 13-inch beams in Fig. 208. 

3. Make a schedule of tie rods and of field bolts required for 
all framing shown in Fig. 208. 

4. Suppose that in Fig. 199 the cast iron columns had a 12-in., 
31J-lb. beam instead of the 15-in. beam, a 7-in. instead of the 10-in. 
beam, and a 9-in. instead of the 12-in. beam, and that all beams were 
flush on top and the other features the same as shown in Fig. 210. 
Make a detail of such a column. 

5. Make a bill of material for the column shown in Fig. 224. 

6. Given a portion of a framing plan as shown in Fig. 226. 
Make shop details of (a) beam No. 1 resting on the column. ( b ) beam 
No. 2, and (c) channels No. 3 and 4. 

7. Given a beam box girder framed between two columns as 
shown in Fig. 227. Make a shop detail of this girder using a uniform 
pitch of rivets of 3 in. in the plates. 

8. Given a lintel composed of two 10-in., 15-lb. channels 
framed between two columns, the channels being placed with the 
flanges turned in, 10 in. back to back, and 14 ft. 8 in. between the faces 
of columns. Make a complete shop detail and order for all parts. 

9. Given a pit under an elevator to be framed with 3 X 3-in., 
6.6-lb. Ts, 17-in. on centers, to receive terra cotta tile. These Ts 
frame between the webs of 15-in., 42-lb. I-beams at each end, which 
are 7 ft. 3 in. center to center. The distance from the top of the beams 
to the bottom of the flange of the Ts is 6 in. Make a shop detail 
of the Ts. 

10. Given a portion of a framing plan as shown in Fig. 228. 
Make a shop detail of beams No. 1 and 2 which are framed between 
columns. 

11. In the above plan make detail covering beams, No. 4 and 5. 

12. Given a 15-in., 42-lb. beam framed between the webs of 
two columns. 20 ft. 8 in. center to center on a line perpendicular to 



250 


STEEL CONSTRUCTION 


the axis of the webs, and the center of one column is 1 ft. 9 in. off 
from the other in the direction of the webs. The webs of the columns 
are \ in. thick. The beam has a 12-ft., 31J-lb. beam framed to it, 
2 ft. 1 in. from the center of one column, the tops being flush. There 
are also holes for two lines of f-in. tie rods. Make shop detail. 

































» 











































II • 





























t 












9 


LA SALLE STATION, L. S. & M. S. AND C., R. I. & P. RAILROADS, CHICAGO 

Frost & Granger, Architects; E. C. & R. M. Shankland, Engineers 
Steel trusses over train shed; span of truss, 215 feet. Note the traveling crane, with three derricks on it, used in setting these trusses- 




















STEEL CONSTRUCTION 

PART IV 


RIVETED GIRDERS 

Functions of Flanges and Web. Riveted girders are made up of 
two general parts (a )—the top and bottom members—which are 
termed, respectively, the top and bottom flanges ; and one or more ver¬ 
tical plates (b), called the web-plate, connecting the top and bottom 
flanges. 

Girders of one web-plate are called single-web girders; of two 
plates, double-web girders; of three plates, triple-web girders. Figs. 
240, 241, and 242 illustrate these different types. 

The function of the flanges is to take the compression and tensile 
stresses developed in the outer fibers by the beam action. The func¬ 
tion of the web is to unite these two flanges and to take care of the 









Fig. 240. 







Fig. 241. 


Fig. 242. 


shear. These functions are distinct. In a rolled beam, the stresses 
are considered to be distributed over the whole cross-section just as in 
a rectangular wooden beam; and this stress varies uniformly from the 
neutral axis. A rolled beam, therefore, is proportioned by using the 
beam formula, and determining from it the required moment of inertia. 

A riveted girder, however, is not a homegeneous section; the 
flanges are separate from the web, except as they are united to it at 
intervals by rivets. For this reason the stress in the extreme fibers on 
the compression and tension sides is considered as concentrated at the 













252 


STEEL CONSTRUCTION 


center of gravity of the flange, and the flanges are considered as taking 
all the compression and tension stress. 

The bending moments caused by the vertical loads acting on the 

girders are considered as re- 
/b Center^Gravity therefore) by the ir 

tension and compression 
stresses, which form a couple 
whose arm is the distance be¬ 
tween the centers of gravity 
of the two flanges, as illustrat¬ 
ed by Fig. 243. 

Proportioning Flanges. 
ft. Referring to Fig. 244, if the 

Fig. 243. bending moment on the girder 


Center 'of Gravity 


Botiorh \r/ gnge 


Center of Grcne/ty 
Top F/an qe 






< 






^Center of 
Bottom 

l = Span Center to Center 

Gravity 

F/anqe 

r of Bearings 



Fig. 244. 


is M, and h is the distance between centers of gravity of flanges then 
M 

y- = F = the tension and compression forces necessary to balance 
the bending moment. 

If f c = Allowable Stress per square inch in compression, and if 
f t = Allowable Stress per square inch in tension', then 
F 

Area required in compression flanges, and 
fc 

F 

~r *- Area required in tension flange. 
ft 



















STEEL CONSTRUCTION 


253 


The values of f c and f t vary with the class of construction in which the 
girders are used. These are generally specified in each case. The 
usual values for different classes of construction are as follows: 

ALLOWABLE VALUES 

For Buildings: 

ft (tension) = 15,000 pounds per square inch, net area. 

] c (compression) = 12,000 pounds per square inch, gross area, re¬ 
duced for ratio of unsupported length to width of flange. 
f s (shearing stress) = 12,000 pounds per square inch, net area. 

For Highway Bridges: 
f t = 13,000 pounds per square inch, net area. 

f c = 11,000 pounds per square inch, gross area, reduced for ratio of 
length to width of flange. 
f s = 10,000 pounds per square inch, net area. 

For Railway Bridges: 
ft = 10,000 pounds per square inch, net area. 

f c = 8,000 pounds per square inch, gross area, reduced for ratio of 
length to width of flange. 
f s = 8,000 pounds per square inch net area. 

The practice regarding the reduction of allowable compression 
stress varies somewhat; but the following formula is a conservative 
one for general use: 

fc . 

1 2 ? 

1 + 5,000 W 2 
where / = Fiber stress to be used in compression; 
f c = Specified fiber stress unreduced; 
l = Length of unsupported flange (in inches); 

W = Width of flange (in inches). 

In ordinary construction, the fact that the two flanges are gener¬ 
ally made of the same section makes it unnecessary in many instances 
to consider this reduced compression-fiber stress. If the unsupported 
length of top flange is long, however, so as to make the section deter¬ 
mined for bottom flange insufficient, then both flanges should be made 
the same aS that required by the compression value. 

When the girder is short, and the web-plate is not spliced, allow¬ 
ance is sometimes made for the portion of the compression and tension 






254 


STEEL CONSTRUCTION 


which the web may carry. In doing this, the net area of the web— 
deducting rivet-holes—is considered concentrated at the centers of 
gravity of the flanges, and as reducing the required area of the flanges 
by an amount equal to £ t h v in which t - thickness of web, and \ 
= depth. When this assumption is made, therefore, the required 


area of each flange is - — \ th v in which / is the compression value for 


the top flange and the tension value for the bottom flange. 

There is a considerable saving in the templet and shop work if 
both flanges are made alike; the extra weight in one flange which may 
be added, will often be more than offset by the saving in shop work. 

It is a very general practice, therefore, to make both flanges alike 
in section, determining this by whichever flange requires to be the 
larger. 

Economical Depth of Web. It will be seen that the areas re¬ 
quired for the flanges are dependent on the depth of the web. Where 
there are no conditions limiting this depth to certain values, it is de¬ 
sirable, therefore, to fix it so as to give the most economical section. 
For a uniformly distributed load, this depth is generally from £ to 
Jg- of the span. Sometimes several approximations of this depth 
can be made, and the corresponding areas determined; and then, by 
computing the weights of flanges and web-plates so determined, the 
most economical section can be chosen. 

In a great many cases, especially in building construction, the 
economical depth cannot be used, because of conditions fixing this 
depth with relation to other portions of the construction. In other 
cases, certain sections of plates and angles must be used in order to 
obtain quick delivery; and accordingly, the depth must be fixed to 
harmonize with these sections. 


Proportioning the Web. As before stated, the function of the 
web is to resist the shear. 

The student should here note that, as explained under “Statics,” 
the loading which will produce maximum shear is not necessarily the 
same as that which causes the maximum bending moment. 

In highway and railway girders, this loading is always different. 
In building construction it is very often different, because certain 
beams may frame into the girder over the support and these beams 
must be considered in determining the shear although they are not con- 




STEEL CONSTRUCTION 


255 


sidered in determining the bending moment. Again, a girder may 
carry a wall, and a portion of this wall may come directly over the end 
supports of the girder. This portion will materially increase the 
shear while perhaps not affecting the bending moment. 

The general statement of loads to be considered in determining 
the shear where all loads are fixed in position, is to include all loads 
which directly or indirectly can come upon the girder, and to deter¬ 
mine the maximum end reaction for these loads. (The determination 
of web shear for moving loads, will be treated under “Bridge Engi¬ 
neering).” Sometimes the shear at one end is greater than at the other, 
in which case the section is fixed by the requirements at the end having 
greatest shear. 

Having determined therefore, the maximum shear, the required 

S 

area of web is — = J th 

Js 

in which S = Maximum shear; 

f s = Allowable shearing stress per square inch of net area of 
web; 

t = Thickness of web; and 
h = Depth of web. 

The net area is assumed as f the gross area. 

Crippling of Web, and Use of Stiffeners. The value of f s to be 
used depends on the clear distance between the adjacent edges of the 
top and bottom flange angles, and upon whether or not stiffener angles 
are to be used. 

The distribution of the shear over the web causes compression 
forces acting at angles of 45 degrees with the axis of the girder, in the 
manner indicated by Fig. 245. The web, therefore, under these com¬ 
pression stresses, is subject to failure laterally, just as a long column. 
The allowable shearing stress must therefore be reduced by a formula 
similar to the column formula, which may be taken as 

12,000 

' 8 " d(? ' 

1 + 3,000 t 2 

in which d c = distance between flanges; and t = thickness of web. 

Either the web must be made thick enough not to exceed this 
allowable stress on a length 1,414 d c, which is the length on a 45-degree 
line between the adjacent edges of flange angles, or this unsupported 





256 STEEL CONSTRUCTION 


length must be reduced by using stiffeners so spaced as to cut this 45- 
degree length down to limits which will conform to the allowable shear¬ 
ing stress given by the 
formula and to the thick¬ 
ness of web which it is 
desired to use. 

Webs less than T 5 ^ 
inch thick are rarely 
used. For greater thick¬ 
nesses, it is a matter of 
economy generally to use 
stiffeners. For very 
heavy loads, however, or 
for long spans, f-inch or 
- 2 -inch webs would be 
used, with or without 
stiffeners, as might be 
required. 

Fig. 245. It will seen f r om 

the above consideration, that, where the shear varies from the end 
towards the center, the required spacing of stiffeners will increase to¬ 
wards the -center, since the area of the web is constant. 

When the shear has reduced to the point where the area of web 
is sufficient to resist buckling on a length of 1.414 d c, then the stiffeners 
may be omitted. A convenient diagram for determining spacing of 
stiffeners is shown in Fig. 246; the use of this diagram will be illus¬ 
trated by a problem. 

Suppose the shear at the end of a girder is 100,000 pounds; and 
the clear distance between flange angles is 22 inches, and the web which 
it is desired to use is 30 inches by f inch. The gross area of web is 
then 11.25 square inches, and the shear per square inch of gross area is 
8,900 pounds. Following up the vertical side of the diagram until the 
line corresponding to 8,900 is found, then following this line until it 
meets the line of a f-inch web, and then looking under this inter¬ 
section to the lower horizontal line, it is found that stiffeners must be 
spaced about 12 inches apart in order to conform to the above con¬ 
ditions. 

If it was desired to find what thickness of web was necessary in 










Shear per square /pc/? of web 







































-UlUL 

jn 

an 

a * 

edr Spacing Stiffeners 


TO 

OO 










In Plate Girders 


















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formula'' D— 55.3 fv —s -- / ► — 

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or f/anqe angles [ 

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258 


STEEL CONSTRUCTION 


order not to require stiffeners, the flange angles being 22 inches apart 
in the clear, this would be determined as follows: 

Follow up the vertical line corresponding to 22 inches as given at 
the bottom of the diagram, until this line meets the line corresponding 
to such a thickness of web that the gross area is sufficient to bring the 
shearing stress within the limit by the horizontal line at this intersection 
of web-line and vertical through 22. 

In this case the nearest intersection is found to be the ^-inch web. 
The area of a 30-inch by J-inch web is 15 square inches, and this gives 
a shearing stress per square inch of 6,675 pounds. The allowable 
stress as given by the diagram is 7,400 pounds; but the T \-inch web 
found to give a shearing stress of 7,640 pounds, whereas the allowable 
shear for a T 7 ^-inch web with angles 22 inches apart is only 6,600 
pounds. 

It would be found more economical to use a f-inch web with 
stiffeners, than a J-inch web without stiffeners. 

Another use of stiffeners is to stiffen the web at concentrated 
loads. The most important case under this head is the reaction at the 
bearings of the girder. Stiffeners are always used here, and they are 
generally placed so that the outstanding legs will come nearly over 
the edge of the bearing plate, as illustrated by Fig. 247. Sometimes 


s6x4'*k'L 


o 

o o 

o 

o o o o o 

o 

o 

o 

o 

o 

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o 

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o 

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o 

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Fig. 247. 


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O 

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o 

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"L 


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o 

o o o 

o 

o~ 

1 



Fig. 248. 


the special nature of the bearing—as, for instance, the disposition of 
column members—makes it desirable to place these stiffeners close 
together, or in three lines instead of two. The fundamental idea is 
to place the stiffeners so as to distribute the reaction in the most direct 
way to the bearing. If this bearing is masonry, the stiffeners will be 
placed so as to give uniform bearing; if a column, they will be placed 
so as to correspond as closely as possible with the line members of 







































STEEL CONSTRUCTION 


259 


the column. Wherever heavy concentrated loads from beams, other 
girders, masonry piers, etc., occur, stiffeners should be used to stiffen 
the web against this concentrated application of load. Stiffeners over 
bearings should be fitted to both the top and bottom flange angles. 
Stiffeners at loads on the top flange need be fitted only to the top flange 
angles. 

Stiffeners used simply to prevent buckling from the shear, need 
not be fitted to either flange. Sometimes stiffeners used for this latter 
purpose are not carried over the flange angles, but stop clear so as to 
avoid the necessity of fillers, as indicated by Fig. 247. It is better 
practice, and more generally followed, to carry these angles over the 
flange angles, as shown by Fig. 248. 

PROBLEMS 

1= Determine by the method previously described the bottom 
flange section of a girder 28 inches deep between centers of gravity of 
flanges, and having a bending moment of 3,500,000 inch-pounds. 
The flange is to be proportioned to carry the whole bending moment. 
Use fiber stresses given for building. 

2. In the above problem, if the top flange is unsupported later¬ 
ally for 20 feet, determine the section of top flange required, using the 
formula given for reducing allowable compression stress. 

3. Given a girder 35 feet long between centers of bearings, and 
carrying a uniformly distributed load of 2,000 pounds per linear foot. 
Assume a web 36 inches deep and 34 inches between centers of gravity 
of flanges. Determine bottom flange section without making any 
allowance for the portion of bending moment carried by the web. 

4. In the above girder, redesign bottom section on the basis that 
the web is not spliced and that it bears a portion of the bending mo¬ 
ment. 

5. Determine the thickness of web required in above girder. 

6. If the girder was 40 feet long, 42 inches deep, and loaded with 
4,000 pounds per linear foot, determine the thickness of web if no 
stiffeners are to be used. Assume flange angles are 6 inches by 6 
inches by \ inch. 

7. Determine thickness of web in above girder which could be 
used with stiffeners, and determine spacing of stiffeners required. 

Solution. In this case the shear at end is 80,000 pounds. From 
the diagram for spacing of stiffeners, it will be seen that any thickness 




260 


STEEL CONSTRUCTION 


of web from T 5 ^ inch up could be used. Where stiffeners are used 
to prevent buckling of web, it is more economical to use a T 5 ^-inch 
web than a f-inch. If the girder was 60 inches deep, probably it 
would not be well to use less than f-inch web, even with stiffeners. 
In this case assume a T 5 ^ by 42-inch web. Area is therefore 13.12 
square inches, and fiber stress is 6,150 pounds. 

From the diagram it is seen that a T 5 ^-inch web with this stress 
per square inch requires stiffeners about 16J inches back to back,, 
This then determines the space of first stiffener from those over the 
bearing plate. Assume two spaces the same as this, and then deter¬ 
mine shear at point say 3 feet 6 inches from the end bearing. This is 
found to be 80,000 — (4,000 X 3.5) = 66,000 pounds. The stress here 
is about 5,075 pounds per square inch of web. From the diagram, 
this is seen to require stiffeners 20 inches apart. Assume two more 
spaces at 20 inches, and calculate sheai;, which is found to be 52,600 
pounds. This gives a fiber stress of 4,050 pounds per square inch of 
web, and requires stiffeners 24 inches apart. Take three spaces at 
this distance, and calculate shear, which is found at this point to be 
28,600. This gives a stress of 2,200 pounds per square inch of web. 
From the diagram the spacing of stiffeners for this fiber stress, in a 
Y^-inch web, is found to be 36 inches. This distance, however, is 
greater than the clear distance between flange angles, which is 30 
inches, and indicates, therefore, that at this point the web is strong 
enough without being stiffened by angles. 

If it is desired to see whether or not two spaces at 24 inches, in¬ 
stead of three as above taken, would have been sufficient, the shear at 
this point can be calculated. This is found to be 36,600 pounds, or 
2,800 pounds per square inch of web. This is seen to require stiffeners 
31 inches apart. This is greater than the distance between flange 
angles, and indicates that the last stiffener could be omitted. How¬ 
ever, it is better to carry the stiffeners a little beyond the actual point 
where the diagram would indicate that they could be dropped; so that 
it would be better to use the last stiffener, as originally determined. 
The spacing of stiffeners at each end of girder is of course made the 
same where the load is uniformly distributed. 

Size of Stiffeners. Stiffeners for concentrated loads and for reac¬ 
tions should have sufficient area to take the whole load or reaction 
at this point. Stiffeners used to prevent buckling are not generally 



STEEL CONSTRUCTION 


261 


calculated, but are made either 3 x 3 x J inch or 4 x 3 x f inch. When 
stiffeners are fitted to the flanges, the outstanding leg should be made 
large enough to come nearly out to the edge of the flange angle. If 
the flange angle is 6 by 6, the stiffener would be perhaps 5 by 3J. 

Cutting Off Flange Plate. In heavy girders the flanges are made 
of angles with cover-plate. Sometimes only one plate is required; 
at other times four or more will be needed. As the maximum moment 
is the moment determining the flange section, and this usually varies 
from point to point, it will be seen that for economy the number of 
plates should be proportioned to the varying moment. Where the 
girder is loaded uniformly, the bending moment is a maximum at the 
center of the span, and varies toward the ends as the offsets to a par¬ 
abola. A convenient way, therefore, to determine for such a case 
where to stop the different plates, is to lay off to scale the span, and 
on this axis construct a parabola, making the ordinate at the center 


represent the required area, from the formula 


M 

fh 


- A. 


A convenient 


method of constructing the parabola will be to lay off the offsets, which 
are determined at different points by the formula 


y= /? as by Fig. 249. 


From this diagram, the point at which an area equal to one of the 
plates can be dropped off, will be found by drawing a horizontal line 
at a distance down equal to the area 
of the plate at the same scale as 
the center ordinate. Where this 
line cuts the line of the parabola, 
will be the exact length of plate re¬ 
quired. Sufficient length should be 
added at each end to enable rivets 
enough to be used to develop in single shear the stress in the plate. 
Usually this will be about 1 foot 6 inches at each end. 

Another method of determining where to drop off plates when the 
load is uniformly distributed, is to use the formula 



x = 



A 1 1 2 
A’ 













262 


STEEL CONSTRUCTION 


in which x = Distance from center to point where area of plate is 
not required; 

A t = Area of plate to be cut off; 

A = Total required flange area at center, 

■ 

L = Span. 

When the loads are concentrated, and the moment does not vary 
uniformly from point to point, the only way is to calculate the moment 
at different points, and proportion the flange and at these points in the 
same manner as at the center. 

PROBLEMS 

1. Given a girder 50 feet long, having a flange section of two 
angles 6 x 4 x J, and 2 cover-plates 10 x f inch. Construct a parabola 
on this length as an axis, and determine the distances between the 
points where from diagram each cover-plate could be left off. 

2. In above girder, determine actual length of cover-plates re¬ 
quired by using the formula for cutting off plates. 

3. Given a girder 40 feet long between centers of bearing, loaded 
with 120,000 pounds concentrated at four points equally distant. 
Determine the bottom flange section, and length of cover-plates. 

Solution. Max M. = 30,000 X 8 X 3 X 12 = 8,640,000 inch- 
pounds. Assume web 36 inches deep, and effective depth as 34 inches; 
then flange stress = 254,000 pounds. This, at 15,000 pounds’ fiber 
. 254,000 

stress, requires ^ = 16.95 square inches. 

In this, as in all calculations of girders, a great many sections 
could be chosen. In all problems the student must use his own judg¬ 
ment as to just what shapes to use in order to make up the section. 
Take 

2 angles 6 x 6 x f = 7.28 (two holes out) 

2 plates 14 x f = 9.75 (two holes out) 

17.03 

Note that in deducting area of rivet-holes from bottom flange, 
the hole is considered 1 inch in diameter, even though f-inch rivets 
are used. If smaller rivets were used, this might reduce the assumed 
diameter of hole to f inch. 






STEEL CONSTRUCTION 


263 


From the manner in which this girder is loaded, it will be seen 
that the points at which the plate can be left oft* will be near the con¬ 
centrated loads. Omitting both plates will leave a net area of 7.28 
scpiare inches; this corresponds to a flange stress of 7.28 X 15,000 = 
109,200 pounds; and to a bending moment, assuming the same effect¬ 
ive depth as at the center, of 109,200 X 34 = 3,712,800 inch-pounds. 
The reaction is 60,000 pounds; and it is therefore seen that the point 
corresponding to this moment is between the reaction and the first 


3 712 800 

load. Its position is found as - ^ ^ = 61.88 inches = 5 feet 1J 

inches. 

If this first plate is carried 1 foot 6 inches beyond this point, then 
its total length becomes 32 feet 7\ inches. 

At the point where the second plate is dropped, the net area is 
12.10 square inches. This corresponds to a flange stress of 12.10 X 
15,000 = 181,500 pounds; and to a bending moment of 181,500 X 34 
= 6,160,000 inch-pounds. 

The bending moment at the load nearest the reaction is 60,000 X 
8 X 12 = 5,760,000 inch-pounds. 

The moment between this load and the next load increases by an 
amount equal to 60,000 — 30,000, multiplied by the distance from the 
load. That is, at a point x distance from the last load, the moment 
will have increased (60,000—30,000) X x X 12 inch-pounds. 

The bending moment which the angles and one cover-plate can 
carry was found to be 6,160,000 inch-pounds. The moment at first 


load is 


5,760,000 

400,000 


= allowable increase to point where 


second cover is required. 

The distance from this first load to the point where it will be 
necessary to add the second cover-plate, is found, therefore, to be 


400,000 
30,000 X 12 


1.12 feet. 


As this is so near the point at which the load is applied, it would be 
better to add a little more than 1 foot 6 inches to this distance, in order 
to carry the plate a little beyond where the concentrated load occurs. 
This would make it necessary to increase slightly the length of the first 
cover from what was previously determined. These plates might be 
fixed, therefore, as 26 feet long and 34 feet long, respectively. 








264 


STEEL CONSTRUCTION 


Spacing of Flange Rivets. The purpose of the rivets through the 
flange is to provide for the horizontal shear. There is a definite rela¬ 
tion between the horizontal shear and the vertical shear at a given 


point, which is expressed by the formula s 


SQ 
= I ’ 


in which 


s = Horizontal shear per linear inch; 

S = Total vertical shear at section; 

Q = Statical moment of the flange about the neutral axis of the 
girder; and 

I = the moment of inertia of the whole section of the girder about 
its neutral axis. 

Having determined the horizontal shear per linear inch, the spacing 
becomes the value of one rivet divided by this horizontal unit shear, or 


d 


V 

s 


For the vertical rivets through flange angles and cover-plates, the 
same formula applies, except that Q is taken as the statical moment 
of the cover-plates only about the neutral axis. 

The above exact method is not the one generally followed in 
spacing rivets, because it is not generally necessary to space the rivets 
so nearly to the exact theoretical distance. It is quite a common 
custom to space these horizontal flange rivets by assuming that the 
horizontal shear is equal to the vertical shear at the section divided 
by the distance between the centers of gravity of the flanges. This 
gives spaces somewhat less than would be required by the formula 
above. 

The vertical rivets through cover-plates are made to alternate 
with the horizontal rivets; and in general, if there are sufficient hori¬ 
zontal rivets, this method will give sufficient vertical rivets. In doubt¬ 
ful cases, the exact method should be used. 

It is customary to vary the spacing of the rivets about every two 
or three feet, or, in long girders, at intervals somewhat greater. This 
involves, of course, the determination of the ^hear at each point where 
a change in pitch is made. 

The minimum distance in a straight line between rivets is three 
times the diameter of the rivet; if j-inch rivets are used, the minimum 
distance, therefore, is 2J inches. This is shown by Fig. 250. This 
fact many times determines the size of flange angles to be used. In 




STEEL CONSTRUCTION 


205 


some cases the horizontal shear determining the pitch of rivets is so 
great that the distance between rivets becomes less than three times 
the diameter of the rivet. The flange stress might make it possible 
to use perhaps an angle with a 4-inch leg; in order to get in rivets 


^ 3d 



Fig. 250. 


Fig. 251. 


enough to take tlie shear, however, it becomes necessary to use an 
angle having a 6-inch leg so as to use two lines of rivets. In such a 
case the horizontal distance between center lines of rivets may be 1^ 
inches, and still the direct distance between the rivets will not be under 
2\ inches. Fig. 251 illustrates this. 

PROBLEMS 


1. Determine the pitch at end of girder having a reaction of 
00,000 pounds, with web-plate 30 inches deep and f inch thick. 

Assume effective depth between center of gravity of flanges, 28 


inches; then approximate horizontal shear per linear inch 


60,000 

28 


2,142. 

The bearing value of a f-inch rivet on f-inch plate is 5,060; there¬ 
fore pitch = = 2-35 or 2 T % inches. 

2. Given the same web as above, with an end reaction of 95,000 
pounds, determine pitch at end. 

Here = 3,400 = Horizontal shear per linear inch; and 


5,060 i ii - n 

= i .49.or 1J inches. 

This makes it necessary to use an angle deep enough to give two 
lines of rivets either a 5-inch or a 6-inch leg. If the pitch between 
rivet lines is 2\ inches, and horizontally between rivets 1J inches, then 
the actual distance between rivets is about 2\\ inches, which is more 
than thfee times the diameter of the rivet. Where the top flange 





















266 


STEEL CONSTRUCTION 


of a girder is loaded directly, as by a heavy wall, it becomes necessary 
to calculate the rivets for direct shear as well as horizontal shear. The 
combined stress on the rivet must not exceed its value, and therefore a 
spacing somewhat less than that determined for horizontal shear above 
must be used. This can best be illustrated by a problem. 

3. Given a girder having a web-plate 36 inches by f inch, with 
an end reaction of 75,000 pounds, and loaded directly on top flange 

with 3,000 pounds per foot of girder, ~ ^ — = 2,206 = horizontal 

shear per inch. Assume a pitch of 2} inches; then 
2,206 X 2.25 = 4,963 = Horizontal stress on rivet; 

^’000 = 250 = Direct vertical shearing force per inch, and 
1 £ 

250 X 2.25 = 560 = Direct vertical load on rivet. 

These forces act on the rivet as indicated by Fig. 252. The 
resultant, therefore, is the square root of the sum of the squares of 


these two forces, and equals 4,994. As 
the value of the rivet is 5,060, this is 
about the nearest even pitch which 
could be used for these combined 
stresses. 


H 



Fig. 252. 


The maximum straight distance between rivets which can be used 
is 6 inches, or sixteen times the thickness of the thinnest metal riveted. 
For a flange having ^-inch angles, therefore, 5 inches would be the 
maximum pitch; or, if a J-inch cover-plate were used, 4 inches would 
be the maximum in rivets through these cover-plates. 

Vertical spacing of rivets in stiffeners does not generally require 
calculation. For end stiffeners there should be at least sufficient to 
take up all the end shear. In other stiffeners the pitch is generally 
made 2\ or 3 inches. 

Flange Splices. In long girders it becomes necessary sometimes 
to splice the flange angle and cover-plates. Sometimes, for purposes 
of shipment or erection, the girder has to be made in two or more 
parts and spliced. 

In splicing the angles, the full capacity of the angles should be 
provided in the splice, regardless of whether the splice is at a point 
of maximum flange stress or not; it preferably should not be so located. 
Angles are used on either side of the flange angles, with the corner 






STEEL CONSTRUCTION 


267 


rounded to fit accurately the fillet of the flange angle, and having the 
same gross or net area as these angles. 

Fig. 253 shows the splice of the top flange of a plate girder. Note 
that the angles are spliced by cover-angles and also by cover-plates. 
In flange splices, provision should be made as far as possible to splice 
each leg of the angles directly and with sufficient rivets to provide 


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for the proportional part of the stress carried by this leg. If cover- 
plates form part of the section of the flange, these should, if possible, 
be spliced at a point where one of the cover-plates is not required for 
sectional area, and then this cover-plate should be carried far enough 
beyond the splice to provide rivets sufficient for the stress in the plate. 
If the plates are of different areas, an additional, short cover-plate 
over the splice would be required, to make up the required area. 

When the shop work has to be very exact and reliable, a planed 
joint is sometimes used to take a portion of the stress by direct com¬ 
pression between the abutting ends. In such cases the cover angles 























































2G8 


STEEL CONSTRUCTION 


should be used, but may be of slightly less area. It is preferable, 
when possible, however, to have the flange fully spliced without relying 
on the planed joint. The number of rivets should be sufficient to 
provide for the full capacity of the flange angles without exceeding the 
value of a rivet. If one portion of the splice is hand-riveted, the values 
must be determined accordingly. Rivets are in double shear or bear¬ 
ing on the angles. 

Web Splices. If the girder has been designed without considering 
that the web carries part of the flange stress, then the web splice need 
have only sufficient rivets to provide for the shear. If the web were 
considered as helping to carry the stress due to bending moment, then 
the splice would have to have sufficient rivets to resist this portion of 



the bending moment carried by the web. In such a case, if two lines 
of rivets each side of the splice are used, and these rivets are spaced 
2 i or 3 inches center to center, they will be sufficient to provide for the 
shear and the bending moment also. In general it is better to use 
such a splice as illustrated in Fig. 254, whether the intention is to pro¬ 
vide for bending moment or not. 












































STEEL CONSTRUCTION 


2G9 


The splice plates should have a net area equal to or a little greater 
than the net area of the web. If possible, the splice should be located 
at a point where the flanges are not fully stressed, so that they can help 
to splice the web. 

PROBLEMS 

1 . As an illustration of the use of the exact formula for pitch 
of rivets, the following problem will be worked out: 

Take the girder given in the problem illustrating the cutting-off 
of flange plate. This girder 40 feet long has a web-plate 36 inches by 
f inch; and section of flange at end consists of two angles 6 x 6 x § inch. 
At point 10 feet from end section, are two angles 6 x 6 x f inch, and 
2 plates 14 x | inch. 

Determine first the pitch of rivets at end where the shear is 60,000 
pounds. The formula is: 



The first step is to determine position of center of gravity of flange. 
As there are no cover-plates, this is taken directly from “Cambria” 
and is 1.64 inches. 

The web is 36 inches; but in all girders where flange plates are 
used, the depth back to back of angles is \ or \ inch more than the 
depth of web, in order to allow for any variation in the depth of plate. 
In this case it will be taken as 36J inches back to back of angle. 

Q - 2 X 4.36 X 16.49 = 143.8 
I = 4 X 15.39 = 61.6 

4 X 4.36 X 16.49 3 = 4,740. 

T VX | X 36 = 1,458. 

6,259.6 

0 60,000 X 143.8 

S = ' 6,259.6 = 1>375 

Pitch - 7 ^? = 3.69 inches. 

1,3/0 

Something less than this would be actually taken—probably 2f 
or 3 inches. 






270 


STEEL CONSTRUCTION 


To determine the pitch at point 10 feet from end, we have to 
calculate the neutral axis of the flange as follows: 

Angles 2 X 4.36 X 2.39 = 20.9 
10.5 X .38 = 4.0 
24.9 

24.9 19.22 =1.3 inches from back of cover-plate to neutral 

axis. 


Q = 19.22 X 17.58 = 338 

1=4 X 15.39 = 61.6 

2 X 19.22 X 1L58 2 = 11,870. 

tVX | X 36 3 = 1,458 

13,389.6 

0 30,000 X 338 

b ” 13,390 

Pitch of rivets = = 6.68 inches. 


757 


The maximum pitch is as stated 6 inches. At this point the actual 
pitch would be made somewhat less—say, 5J inches. 

As a comparison with the foregoing results, it will be well to note 




i*. s’-o" 0 

4 5 L 0" 7 -5-0" 5'-0" ^ 5 l 0" . 


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£ 30-o' C/ear 




Fig. 255. 


the pitch as determined by the approximate method, using the distance 
between centers of gravity of flanges. At the ends, we have 


60,000 

33 


= 1,820 


TV 1 5,060 . _ 

Pitch = -- = 2.78 inches. 

IjOiiU 

It will be seen that this approximate method gives some closer 
pitch than the more exact formula. 

2. Given a girder 30 inches by T 5 ^ inch, 30J inches back to back of 













J Girders Like This 

Mark AL Ate A3. 


Bill or Mat erial Bor 3 Girders. 


/ TEN 

NO. 

or 

PCS. 

Kind 

Size 

Length 

Work 

B 

12 

■StifFr. Ls 

5*3"*i 

2 

si 

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C 

24 

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Fig. 256. 







































































































































































































































STEEL CONSTRUCTION 


271 


flange angles. The flange section is made up of two angles 4 x 4 x f 
inch. The end shear is 42,000 pounds. Determine the pitch of rivets 
by the approximate method. 

3. Given a girder 42 feet long, loaded with a uniformly distrib¬ 
uted load of 7,000 pounds per linear foot. If the web is 42 inches by 
t t 6 inch, and the flange section at the end is made up of two angles 
6 x 6 x \ inch, and 1 plate 14 x b inch, and distance back to back of 
angles is 42J inches, (a) determine the pitch of horizontal rivets 
through web; ( b ) determine the pitch of vertical rivets through flange 
plates. Give two solutions of (a) and ( b ), using the exact formula and 
the approximate method based on distance between centers of gravity 
of flanges. 

Answers —(a) If inches by the approximate method, 
l^f inches by the exact method. 

(b) inches by the approximate method. 

6 f inches by the exact method. 

Note that where pitch of vertical rivets through cover-plates is 
determined by the approximate method, they are simply assumed as 
alternating with the horizontal rivets. If there is only one line of 
horizontal rivets through flange angle and web, and one line of vertical 
rivets, then, by the approximate method, the vertical rivets through 
cover-plates would come centrally in the space between the horizontal 
rivets. If there are two lines of horizontal rivets, and one line of 
vertical, the vertical rivets would still alternate with the inner line of 
horizontal rivets, or center over the outer line of horizontal rivets. 
This would hold good so long as the spacing in this way did not exceed 
6 inches, or sixteen times the thickness of plate. If this were the case, 
then the vertical rivets would be made to center over each line of hori¬ 
zontal rivets. The same practice as regards vertical rivets would be 
followed in case both horizontal and vertical legs had two lines of 
rivets. The formula for exact determination of rivet pitch shows that 
the above approximate methods are within the limits which would be 
determined if the exact method was used. 

Shop Details of Girders. Fig. 256 is a shop detail of a simple 
plate girder of one web. It will be noted that the detail covers only 
one-half the girder. Where the girder is exactly symmetrical about 
the center line, it would be a waste of time to draw up both halves. 
In such cases it is sufficient to mark the center line and mark the draw- 



272 


STEEL CONSTRUCTION 


ing so that it will be clear that the other half is the same. In some 
cases where there is only a slight difference, as at the ends between 
the two halves, it is still unnecessary to detail more than half the girder; 
in such cases a special detail of the end which is different should be 
added. 

This girder rests on a brick wall at each end; and therefore the 
end stiffeners are placed over the outer edge of bearing plate, as shown. 
A wall rests on top of the girder, and the intermediate stiffeners are to 
support the flange when the main pier lines come down, and to stiffen 
the web for the concentrated beam loads. 

A girder such as this would probably come into the drafting room 
for details with only such information as is given in Fig. 257. 

In many cases, even the loading on the girder might not be given. 
In such case, it would have to be calculated from the general plans 



showing amount and distribution of floor and wall loads. If the loads 
had been uniformly distributed, details might have been made by 
determining the capacity of the girder, as noted below. 

The first point to be determined is the size of the bearing plate. 
The reaction is 65,000 pounds; and, allowing a safe bearing on the 
stone template of 25 tons per square foot, this requires about 1.30 
square feet. A plate 12 by 16 inches, therefore, will be sufficient. 
Applying the formula given on page 97 of Part II, the required thick¬ 
ness is found to be .26 inch; a steel plate f inch thick is used here, 
although i-inch plate might have been used. 

The size of the bed-plate having been fixed, the spacing of all 
the stiffeners is the next thing to determine. The end ones are fixed 
at 12 inches back to back. As the piers come down on top of the 
















STEEL CONSTRUCTION 


273 


girder, it will be sufficient to use one stiffener in the center of each 
pier; if the pier was very heavy or over 3 feet, it would be well to use 
two under each pier. The measurements given in the diagram (Fig. 
257), therefore, fix the other stiffeners. It is then necessary to look 
into the shear on the web to see if stiffeners are required on this ac¬ 
count. Referring to the diagram (Fig. 246), it is found that for a f- 
inch web and 18 inches between edges of flange angles, the allowable 
shear per square inch of web is 6,800 pounds. The actual shear is 


70 000 

Q ’ -3 = 6,750 pounds, which is therefore entirely safe without stiff- 
50 X 

eners, as the shear just one side of the end is 11,000 pounds less. 
Looking new at the horizontal rivet spacing, we find, at the end, 


65,000 _ 0 _. . . . . . . 

s = — = 2,320 = approximate horizontal shear per inch. 

28 


Some engineers use the distance between pitch lines of flange 
rivets, or, in case of double pitch lines, the mean between the two, 
instead of using distance between centers of gravity for determining 
the approximate shear. In this case the result would be: 

65,000 9 CQH 1 

^ = 2,630 pounds. 


The bearing value is the least for these rivets, and may be taken 
at 5,060; the end pitch, therefore, is —jgjj = 1*92 inches. 

It is always better to space a little under the calculated pitch; 
for this reason If inches was used. 

The loads being concentrated, the shear is practically constant 
from the end to the first stiffener; anti the only other point to consider 
is to space from each stiffener so as to conform to the standard gauge 
in the stiffener angle, and to keep this where previously fixed, leaving 
room from the back of angle to drive first rivet. The distance back 
to back being 5 feet 2\ inches, and the standard gauge in one case 
2 inches and in the other If inches, the distance center to center of pitch 
lines in stiffener is 5 feet 6f inches. It is well to leave not less than 1 
inch, and better 1} inches, from the back of a stiffener to first rivet so 
that it can be easily driven; leaving If inches will just allow for 40 
spaces at If inches. 






274 


STEEL CONSTRUCTION 


The shear just to the right of the first stiffener from the end, is 
25,000 pounds; therefore, s = ^ = 1,010 pounds. 

The direct shearing force from the pier load is — = 1,250 
pounds per inch. 

If we assume a pitch of 3 inches, this brings 3,750 pounds on each 
rivet, and the diagram of stress would be as illustrated in Fig. 252, the 
resultant stress being about 4,850 pounds. A pitch of 3 inches could 
therefore have been used and need not have been continued much 
beyond the pier lines. In order to keep the pitch constant, however, 
and be somewhat under the required pitch, 2| inches was used. Simi¬ 
larly, the pitch in center way is made 3 inches, although somewhat 
larger pitch might have been used. 

The actual required pitch through flange plates would be found 
much less than shown, since there are four lines of rivets instead of 
two as is commonly the case in girders of this length. In order to 
simplify the shop work, however, they are detailed the same spacing. 
It is well to note that in such cases the rivet through flange plate on 
the gauge line nearest to the vertical leg of flange angle, comes opposite 
the vertical rivet in flange line farthest from the horizontal leg. This 
is to give all possible room for riveting, and also because it distributes 
the rivets more uniformly. 

The bottom flange spacing is made the same as top, and differs 
only in having the rivets through bearing plates countersunk, with 
open holes for anchor bolts. 

The bill of material should be clear after explanation given in 
Part III for bills of columns. 

Fig. 258 shows the detail of a two-web girder. This girder car¬ 
ries a wall on a street front, and is one of a continuous line of several 
girders. The right-hand end is at the corner of the building; and the 
open holes shown are for connection of a girder on the other street 
front. The girder rested' on steel columns, and the arrangement of 
the line members of the columns determined the spacing and arrange¬ 
ment of the end stiffeners on the girder. 

The column section coming under right-hand end is shown by 
Fig. 259. The stiffeners at the extreme left end are simply for con¬ 
nection to similar stiffeners on the end of the girder coming against 







r-7 


Bill or Material for One Girder 


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OtiEi Girder Lire This Mark No. 7 

'An Rn'et's i 
An Open Ho/es id 
Pa/nr One Coat Graph/re 



Fig. 258. 


























































































































































































































































































































































k 

























































































































































































STEEL CONSTRUCTION 


275 


this one. The intermediate stiffeners are for support of flange under 
centers of brick piers. 

The bottom plates were made 1 inch larger than the top plates for 
the purpose of securing the ornamental fascia. 

In the calculation of the rivets of a two-web girder, the shear is 
assumed to be divided equally on the two webs; 
and therefore each line is calculated as before 
described, except that the shear used is one-half 
the total. It should be noted, also, in such 
cases, that the rivets are in single shear. 

One plate must, of course, be made the 
full length of the girder. The length of the 
other plate is determined as previously de¬ 
scribed, and a length added at each end suffi¬ 
cient to get rivets equal to one-third the capacity 
of the plate. In this case, the net area of the plate being about 8.2 
inches, the capacity is 123,000 pounds; and the required number of 
rivets in single shear is 10, or 5 in each line. 

It should be noted that in two-web girders it is possible to have 
flange angles only on the outside of the web, as the only way inside 
angles could be riveted would be by working a man from the end in 
between the webs. This is ordinarily impossible on account of the 
small space between, and would always be too expensive to justify 
such designs. 

Fig. 260 gives the detail of a three-web girder. This girder is in 
the street front of a modern steel-framed office building, and spans 
the large store fronts which are made possible by stopping one of the 
main lines of columns on top of this girder. The girder rests on col¬ 
umns at each end, as shown by Fig. 261, and is symmetrical with 
respect to the center line. It will be noted from Fig. 261 that the 
column carrying the end of this girder is practically made up of two 
columns riveted together through their flanges. This construction 
permits the heavy girder to get a bearing directly over the column 
shaft, and continues in a direct line the axis of the column section 
above and the portion of this column carrying these upper sections. 
This girder also carries the floor beams, which frame into the bottom 
flange as illustrated in Fig. 262. 

There are some points of a practical nature which should be 















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2 Girders Like This 
Mark Jrd Floor B 3cC. 


Bill of Ma t rial eqr £ Girders 


Inn 

No. 

or 

PC'S 

Kind - 

Size 

Len 

0 TH 

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WORK 


£ 

Web Pis 

36 "* f 

35 

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Girders symmetrica/ about center line 
except as noted 


Fig. 260 






















































































































































































































































































































































































































































































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_ STEEL CONSTRUCTION 277 

noted on tins detail. In a heavy girder of three webs, there are prac¬ 
tical difficulties to be met with in riveting. These must be considered 
and provided for in making the details. 

The steps in assembling this girder would be: 

(1) Rivet up the central portion, consisting of web and four 
angles. 

(2) Rivet the top and bottom flange plates to this central por¬ 
tion of the girder. 

(3) Rivet up each side portion, consisting of web-plate and two 
angles. 

(4) Rivet each side section to the flange plates, which have pre¬ 
viously been riveted to the central portion. 

It will be noted that the position of stiffeners is somewhat different 




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Part SectionaI Elevation 


Elevation of Girder 


Sectional Plan 
of Girder 


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oooooooooooo^ 

■A-O-Oiri r\r^c 

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QOOOQOOOOOOOQ 



Fig. 262. 


from what has previously been described. The stiffeners A and B at 
the end are placed so as to come down directly over the line members 
of the column below. The stiffeners C and D are placed so as to 









































278 


STEEL CONSTRUCTION 


come over the shear plate on the column. B and D are also so placed 
that they can be riveted together and thus form a plate stiffener be¬ 
tween the three webs. To rivet up B and D, it is necessary to rivet 
them together first; then rivet D to the side webs and angles C before 
these side webs are assembled with the central web. After the side 
webs are assembled, B can be riveted to the central web. 

The stiffeners at the center of the girder are arranged to come 
under the line members of the column resting on the top flange of 
girder, and also to serve as plate stiffeners for the webs. 

The method of procedure for riveting up these stiffeners is some¬ 
what different from that used in case of the end ones. In this case, B 
and H would be riveted together, and then B riveted to the central 
web before the side webs are assembled. 

In order to rivet H and G to the side webs, it is necessary to pro¬ 
vide a hand hole in each side web as shown, so thaf these rivets can 
be held on the back side while being driven up after the side webs are 
assembled. 

In three-web girders the distribution of the shear over the three 
webs depends to a considerable degree on the way in which the loads 
are applied. It is generally considered that the center web takes the 
iarger proportion, sometimes as much as f, and the side webs take 
the remainder equally. These webs should always be stiffened so as 
to distribute all loads as much as possible over all three webs. 

The designer, in choosing his sections, will necessarily make an 
assumption as regards this distribution; and this should be indicated 
on the diagram. Practically the pitch in all three webs and flange 
angles would be made the same, this being determined so as to provide 
for the maximum shear according to the assumption as regards dis¬ 
tribution. The actual number of rivets may vary in the different por¬ 
tions, because of angles being used which may allow of only one line 
of rivets, as in the case shown in Fig. 260. 

The detail of connection of floor beams to girder is made special 
because of the awkward relation of beams to girder flanges, which 
"elation could not be changed; only a single angle could be used for 
the connection if this was to be riveted on, and this had to be shipped 
riveted to girder rather than beam. It would have been possible to 
have a double-angle connection by using an intermediate plate and 
two side plates; but this would have added to the expense of erection, 





Bill of Material For One Girder 


Iron 

NO 

OF 

pc's 

Find 

Size 

Length 

WORK 

Feet 

In. 


/ 

weo pi. 

jo" '* J ' 

13 

z 



z 

- 

Z&'x'J" 

5 

5i 

Countersunk 


4 

F/ge Is 

6*6 "*k" 

13 

Z 



/ 

PL 

Z4'F £ 

13 

Z 



/ 

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14 "*- $ 

// 

Hi 



o 

£ 


14 "* /£" 

5 

5i 


A 

/ 

Stiff Y L 

5x3f*f 


54" 

Pined Tog 5 Bottom 

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STEEL CONSTRUCTION 


279 


and sufficient rivets for the reaction were obtained by the single angle. 

It will be noted that some rivets near these connections are shown 
flattened in the bottom flange to clear the flange of beams; also, in the 
elevation, some rivets are shown countersunk to clear the angle con¬ 
nection. Rivets are also shown countersunk where the cover-plates 
are left off, because there is not room to extend the plate beyond the 
last rivet without interfering with the next rivet. All such cases of 
countersinking or flattening rivets to avoid stiffeners or ends of flange 
plates, are to be avoided wherever possible, as they are objectionable 
and expensive. They can generally be avoided by changing the rivet 
spacing somewhat at such points. In the case shown in Fig. 260, the 
girder is such a heavy one, and the rivet spacing so close, that it was 
better to countersink rather than have the wide spacing otherwise 
necessary. 

The end view shows open holes for riveting angles to the main 
column angles as shown in Fig. 261. This practice is objectionable 
for light girders, as previously noted in Part II, and where it is possible 
to properly brace the girder and column connection in any other way. 
In the case of a heavy girder such as this, where the deflection would 
be slight, it is not so objectionable, especially if these rivets are not 
driven until after the columns are carried up and the dead weight of 
construction is put upon the girder. 

The bill of material should be carefully followed through as 
illustrating points previously mentioned. 

Fig. 263 shows a single web-plate girder which carries the wall 
section over an entrance doorway, and also a column line on its canti¬ 
lever end. 

The center lines of the supporting column and of the column 
above, are shown on the plan of bottom flange. Fig. 264 shows the 
girder in its relation to the stonework, and the method of securing 
same to the girder. 

The stiffeners G are arranged to come directly over the line mem¬ 
bers, and the shear angles on column below. The stiffeners A, E, 
and F are similarly arranged with respect to the column above carried 
on the end of the girder. It will be noted that this girder is not sym¬ 
metrical about its center line, and therefore the detail of the whole 
girder is shown. It should be noted also that the concentration of 
loading at one end makes it necessary to increase the web greatly to 



280 


STEEL CONSTRUCTION 


provide for the shear. For this reason a ^-inch plate is riveted on 
each side over the flange angles and carried to a point beyond the cen- 



ter of column bearing where the area of the web alone is sufficient 
for the shear. This end being the point of maximum moment, also, is 
the reason for the increased flange area here. 

Floor beams frame to this girder in the same relation as in the 
case of the three-web girder shown in Fig. 260; but as this is only a 
single web, the connection angles can be riveted to the beam. As 
the beam must be cut to clear the bottom flange angle, this necessi¬ 
tates a filler between the web and the connection angles on beam. 

Note that where brackets or similar riveted members occur on a 
girder, it is better to give a separate section for the details of riveting 
of these members. The end view, and sections A, B, C, and D, show 
the details for these brackets supporting the stonework, and show the 
various details necessary to conform to the position and spacing of 
stiffeners on the girder. 

In a girder loaded as this is, there should be sufficient area in 
each set of stiffeners coming under the column above and over the 



































lO 

CO 

CM 

U 

Ph 















































































282 


STEEL CONSTRUCTION 


supporting column, to provide for the shear; and these stiffeners 
should be fitted to top and bottom flanges. 

PROBLEMS 

Make a complete shop detail, at a scale of f inch to 1 foot, of a 
single-web plate girder 30 feet long clear span, resting on a brick wall 
at each end and carrying a load of 60 tons distributed as shown in Fig. 
255, The web-plate is 30 inches by f inch; both flanges have the 
same section, and each is made up of two angles 5 x 3^ x \ inch (long 
leg horizontal), and two cover-plates 12 inches by x 5 ^ inch. A 15-inch 
42-pound beam frames to the girder on each side in the position indi¬ 
cated by loads. The top of the beams is lj inches below the back 
of the flange angles. The beams are to rest on suitable shelf angles, 
with shear angles beneath, and have side connection angles riveted 
through web of girder to brace them laterally. Determine proper 
number of rivets and character of these connections. Determine 
number and spacing of stiffeners required. Use in addition stiffeners 
just one side of each beam connection. 

Standards in Detailing Trusses. Figs. 265, 266, and 267 show 
details of various types of trusses. The same remarks made previous¬ 
ly for girders apply to trusses wherever they are symmetrical about the 
center line. 

Fig. 277 shows a strain sheet of the truss detailed in Fig. 266. 
This is the form in which the information is generally given to the 
draftsman for detailing. At other times the information may be given 
only by the general drawings, in which case the loads and measure¬ 
ments would have to be obtained from them. 

It will be noted that the same general method of detailing and 
dimensioning is followed in all cases. The strain lines are laid out 
first; these lines should always intersect at the panel points; and the 
strain lines of the members over a point of support should intersect 
over the center of bearing. The strain lines should be theoretically 
the center of gravity lines of the members; it is more common practice, 
however, to use the pitch lines of the angles as the strain lines^ as these 
lines do not vary materially from the center of gravity lines, and much 
confusion is thus saved. In heavy trusses, however, where the chords 
are made up of side plates and angles, the strain lines for the chords 
should be the center of gravity lines, as the difference between these 
lines and the pitch line of the angle would be considerable. 






co 

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284 


STEEL CONSTRUCTION 


Many times the position of one or more panel points will be fixed 
by some features of construction such as a monitor or a hanger for 
shafting, or rod for balcony, etc.; as illustrated by Figs. 267 and 280. 
Wherever such concentrated loads are fixed, there should be a panel 
point, if possible, as otherwise the chord must be materially increased 
to provide for the bending strains produced by the load acting between 
panel points. The panel points being fixed, and the strain lines drawn, 
the lines showing the size and shape of each member are drawn. 

Completeness of Measurements. In dimensioning a detail the 
draftsman should bear in mind all the steps he has to. take to fully 
lay out and fix all the members and connections, and should remember 
that information must be given to enable the templet maker to go 
through the same operations. 

1 . There should be measurements center to center of each panel 
point along each member. These are calculated, never scaled. 

2 . There should be a line of measurements along each member 
from panel point to panel point, fixing each rivet or hole with respect 
to this panel point. 

3. There should be a measurement center to center of the end 
panel points along the top and bottom chords and the vertical or in¬ 
clined end members, 

4. There should be over-all measurements of the above mem¬ 
bers. 

5. There should be a measurement from the end of each piece to 
the first rivet or hole, and each piece should have its size and over¬ 
all length specified. 

6 . Each sloping, member should have its slope indicated by a 
triangle of which one side is 12 inches and the other side inches and 
sixteenths. 

7. Each piece should preferably be given a shop mark, to facili¬ 
tate assembling. 

To fix the measurements noted under (2), it is often necessary to 
make a full-sized or large-scale layout drawn very accurately so as to 
be able to scale closely the distance from panel point to first rivet, 
and to be sure of plenty of clearance and yet have the members fit 
closely. 

After the first hole is fixed, the others are spaced 2\ or 3 inches 
apart for the gusset connections. The number of rivets is of course 




X 


Derails of 
Rod Suspension 


2 Trusses Lire This 
Mark A 

5 hip //v 2 P'C'5. 


All Open Holes rl E xeept Noted 
AH Rivers /' 

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All Washers 2s r a Exeept for <?j Members 

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. 


. 


































STEEL CONSTRUCTION 


285 


determined from the strain sheet and the value of the rivet; f-inch 
rivets are generally used, and gusset plates T 5 ^- or f-inch. Where 
strains are very heavy and it is desired to avoid larger gussets, thicker 
plates can be used. 

The measurements noted under (5) will be fixed by the above 
full-sized layout. It should be carefully borne in mind that such a 
layout is worse than useless unless it is very accurate, and therefore 
care should be taken to insure accuracy. 

Special Notes and Details. As regards the shop marks noted 
under (7), each shop has a different practice. A convenient form, 
however, is to call the top chord “T. C. 1,” “T. C. 2” etc.; the bottom 
chord “L, C. 1,” “L. C. 2,” etc.; the verticals “V 1,” “V 2,” etc.; the 
diagonals “D 1,” “D 2,” etc. 

The exact size and the cuts of the gusset plates are generally 
left to the templet maker; they can be given, however, if it is desirable 
to do so, by adding the necessary measurements, which should be 
obtained from the full-sized layout of the joint. 

Sometimes, in long trusses, it becomes necessary to draw the 
elevation of the truss as outlined above, and to supplement this by a 
larger-scale drawing of each joint, this larger drawing giving all the 
measurements of the connections as related to the panel point, and 
the smalier-scale elevation giving the general measurements. 

Where it is not essential for appearance or for compactness *of 
details to cut the angles on a bevel parallel to the abutting members, 
as is shown by some of the drawings, a square cut can be used and will 
somewhat simplify the shopwork. 

Gussets should always be cut as closely as possible, both for 
neatness in appearance and for saving in weight. 

In detailing, always show gussets, where possible, of such shape 
that they can be cut from a rectangular plate, using one or more of 
the sides of the original plate, and shearing off only where necessary 
for compactness of detail. 

Compression members made of two angles should always be 
riveted together through a washer at intervals of two or three feet. In 
general, it is good practice to follow this for all members , tension as 
well as compression, as it stiffens the truss against strains in shipment 
and against possible loading not considered in calculations, and the 
extra cost is inconsiderable. 



286 


STEEL CONSTRUCTION 


Illustrations of Shop Details. Fig. 268 shows a parallel chord 
truss carrying a floor, roof, and monitor load. Figs. 269, 270, and 271 

show the connection of 
wood purlin under mon¬ 
itor girder to steel truss. 
The floor in this case 
rested directly on the top 
chord, which therefore 
brought bending strains 
as well as direct com¬ 
pression; for this reason 
the channel section was 
necessary. Note that for 
determining number of 
rivets in each member, 
one-half the stress would 
be considered, and the rivets taken at their single-shear value. Tie 
plates are used at intervals to stiffen the lower flanges of the channels 
forming the top chord. 

Fig. 272 shows the strain sheet for another parallel-chord truss 
74 feet long, center to center of bearings. This truss carries a roof 




load assumed as 40 pounds live and 25 pounds dead per square foot, 
and also carries in the bottom chord a ceiling load of 15 pounds per 
square foot. 

The roof beams span from truss to wall, which is 26 feet. On 
account of the construction and the long span, the wood framing is not 
considered as bracing the truss, which is therefore unsupported later¬ 
ally except at the center where a steel strut is provided. 


































Fig. 268 

























































































































































































































































































































































































STEEL CONSTRUCTION 


287 


The manner of working out 
the stresses of such trusses by 
the analytical method, will be 
given below. 

In all statically determined 
structures, there are three equa¬ 
tions which must be true in order 
that the structure shall remain in 
equilibrium: 

1. The algebraic sum of the 
moments, about any point, of all 
the external forces acting on the 
structure, must be zero. If this 
is not the case, there will be a ro¬ 
tation of the structure about this 
point. 

2. The algebraic sum of all 
the external vertical forces must 
be zero. 

3. The algebraic sum of all 
the external horizontal forces 
must be zero. 

Both these latter conditions 
are evidently essential for the 
equilibrium of the structure. 

In a truss loaded solely with 
vertical forces, the first two con¬ 
ditions are the only ones which 
would be used. If the truss is 
acted on by a wind load which 
has a vertical and horizontal 
component, then the third con¬ 
dition needs to be considered. 

In the strain sheet given in 
Fig. 272, the first thing to deter¬ 
mine is the panel load. The load 
at each top panel is 26.25 X 65 X 
load is 26.25 X 15 X 6.17 = 2,400 



6.17 = 10,500; the bottom panel 
. Having determined these, and 



























288 


STEEL CONSTRUCTION 


noted them as indicated on the diagram, the only other external 
force to determine is the reaction. As the truss is symmetrically 
loaded, the reactions are equal, and each-equal to half the total load, 
or 77,400 pounds. 

Suppose the top and bottom chords and the diagonal of this truss 
were to be cut through on the line AB, as shown in Fig. 272. It is 
evident that, if the truss were then loaded as shown by the diagram, 
the portions of the top chord on each side of this cut would push 
against each other, and the portions of the bottom chord on either 
side would tend to pull apart, and the portions of the diagonal on 
either side would tend to pull apart. Unless there were some way of 
transferring from one side to the other these forces tending to push 
together and tear apart, the truss would not stand. It is therefore 



the reaction of the portion of the truss on one side of the section AB, 
acting upon the portion on the other side along the lines of the different 
members, which holds the truss in equilibrium. If therefore the por¬ 
tion of the truss to the right of AB is considered as taken away, and if, 
along the lines of the top and bottom chords and the diagonal, forces 
are applied of the same intensity as the forces which resulted from the 
reaction of the portion on the right and which held the truss in equilib¬ 
rium, then these forces can for the time being be considered as ex¬ 
ternal forces, and the intensity of them will be such as to fulfill the 
three conditions of equilibrium as regards the external forces. This 
condition is indicated in Fig. 273. It will be seen that these forces 
acting along the lines of the members of the truss cut by the section are 
the actual stress in these members necessary to maintain the truss in 
equilibrium. The stresses produced in the members of a structure 












STEEL CONSTRUCTION 


289 


by the action of the loads, are called the “internal” or “inner” forces, 
in distinction from the “external” forces or “loads.” 

Any section, such as AB, cutting three members, gives three 
stresses to be determined. The top and bottom chord stresses are 
determined by using the condition that the algebraic sum of the mo¬ 
ments about any point is zero. For the top chord, the point chosen is 
the intersection of the bottom chord and the diagonal. The moment 
of the stress in these two members about this point, is therefore zero, 
and this leaves only the moment of the top chord stress, which must 
then be equal to the moment of the loads about this point. 

In a similar manner, taking moments about the intersection of the 
top chord and the diagonal, leaves only the moment of the bottom 
chord stress to be determined, which must equal the sum of the mo¬ 
ments of the loads about this point. 

In Fig. 272 these top and bottom chord stresses are determined 
by taking sections through the truss at the left of each panel point. 
These top chord stresses will be worked out below. 

Stress in ab : 

77,400 X 6.17= + 476,000 
6,450 X 6.17 = - 39,500 

+ 436,500 ft. lbs. = Moment to be balanced by mo¬ 
ment of stress in top chord. 

Stress in ab = = + 64,700 lbs. 

Stress in be: 

77,400 X 6.17 X 2 = + 955,000 

12,900 X 6.17 X 2 = - 159,000 
M of be = + 796,000 

Stress in be = 7 - ~ ^ = + 118,000 lbs. 

6.75 

Stress in cd: 

77,400 X 6.17 X 3 = + 1,430,000 

12,900 X 6.17 X 4.5 = - 357,000 

M of cd = + 1,073,000 

Stress in cd = = + 159,000 lbs. 

Stress in de : 

77,400 X 6.17 X 4 = + 1,910,000 

12,900 X 6.17 X 8 = - 637,000 

M of de = + 1,273,000 

Stress in de = = + 188.500 lbs. 










290 


STEEL CONSTRUCTION 


Stress in ef: 

77,400 X 6.17 X 5 = + 2,390,000 

12,900 X 6.17 X 12.5 = - 995,000 

M of ef = + 1,395,000 

Stress in ef = ^ = + 207,000 lbs. 

0.75 

Stress in fg : 

77,400 X 6.17 X 6 = + 2,860,000 
12,900 X 6.17 X 18 = - 1,430,000 
M of fg = + 1,430,000 

Stress in fg = = + 212,000 lbs. 

0.75 

In explanation of the above, it will be noted that the moments of 
those forces causing right-handed rotation are designated “ + ” 
(plus), and those causing left-handed rotation are designated “ — ” 
(minus). Also note that the moment at any point consists of the 
moment of the reaction which for the left-hand reaction causes a 
positive moment and of the moment of the panel loads (including those 
over the end) which cause negative moment. As these panel loads are 
all equal, their moment can most easily be obtained by multiplying 
this panel load by the panel length and by the sum of the number of 
panels detween the origin of moments and the loads. Take for ex¬ 
ample the stress in cd; there is one full panel load distant one panel 
length, and a half-panel load distant two panel lengths; combined, 
these equal one full panel load distant two panel lengths. 

As a check on the moment at the center, it is well to calculate 
in a different manner. As this is the point of maximum moment, this 
moment is the sum of the maximum moments which each load can 
produce. Or it is the sum of the reaction of each panel load, multi¬ 
plied by the distance from the reaction to the panel point. Therefore, 
as a check, we have: 

M = 12,900 X 6.17 X 18 = 1,430,000 foot-pounds. 

In a similar manner, the stresses in the bottom chord would be 
determined, taking moments about the top chord intersections with 
the diagonals. 

There is a simpler way, however. If a section is taken along the 
line C D, and the portion to the right is removed as shown by Fig. 274, 
it will be seen that—just as was explained for the section A B—the 
forces acting along the lines of the members cut are the stress in these 







STEEL CONSTRUCTION 


291 


members necessary to maintain equilibrium. Since the forces along 
ab and ij are horizontal, and are the only horizontal forces acting upon 
the structure, then these two must 
be equal in order to fulfill the con¬ 
dition stated—that the sum of the 
horizontal forces equals zero. This 
determines all the bottom chord 
stresses from the top chord stresses. 

Direction of Stress. A stress 
acting toward the portion of the 
truss not considered removed, is 
'positive and is compression. A stress 
acting toward the portion consider¬ 
ed removed, is negative and is ten¬ 
sion. The direction in which the stress must act is determined by 
the direction of the resulting moment of the external forces. If these 
produce right-hand rotation, then the stress in the member must pro¬ 
duce left-hand rotation in order that the algebraic sum of the moments 
shall be zero. Therefore, in the case of the top chord stresses pre¬ 
viously illustrated, since the resulting moment of the external forces 
is always positive, the moment of the stress in the chord must be nega¬ 
tive or act toward the portion not removed, and the stress is therefore 
compression. 

In the case of the bottom chord, this stress must act in the op¬ 
posite direction to the stress in the top chord, and is therefore tension. 

Stress in Verticals. This is determined by the condition that 
the algebraic sum of the vertical forces must be zero. Taking a sec¬ 
tion similar to C D, the only vertical force, aside from the loads acting 
on the truss, is the stress in the vertical member cut. This stress, 
therefore, equals the algebraic sum of the external forces on the left 
of this section, or the shear, and is opposite in direction or acts down¬ 
ward toward the portion of the truss not removed; the stress therefore 
is compression. 

Stress in ah = 77,400 - 1,200 = + 76,400 
“ “ bi = 77,400 - 8.850 = + 68,500 

“ “ c j - 77,400 - 21,750 - + 55,650 

“ “ dk = 77,400 - 34,650 = + 42,750 

“ “ cl = 77,400 - 47,550 = + 29,850 

“ “ fm = 77 t 400 - 60,450 = + 16,950 

“ “ gn panel load = + 10 -''OO 








292 


STEEL CONSTRUCTION 


This latter stress in gn is obtained by taking the section around 
the panel point g, thus cutting only the top chord and the vertical. 
If the section was taken any other way through this vertical, it would 
cut a diagonal, and it would be necessary to determine the vertical 
component of this stress before the stress in the vertical would be 
known. 

Stress in Diagonals. This is determined by taking sections 
similar to A B, and determining the vertical component of the stress 
in the diagonal. This vertical component must equal the algebraic 
sum of the vertical forces on the left, or the shear at the section. The 
relation of the actual stress in the diagonal to the vertical component, 
is the same as the relation between the length of the diagonal and the 
vertical depth. In this manner the stresses are worked out below: 

Stress in ai = 1.35 X 70,950 = — 96,000 
“ “ bj = 1.35 X 58,050 = - 78,500 

“ “ ck = 1.35 X 45,150 = - 61,000 

“ “ dl = 1.35 X 32,250 = - 43,700 

“ “ em = 1.35 X 19,350= -26,200 

“ “ fn= 1.35 X 6,450 = — 8,750 


The direction of stress in these diagonals will be understood from 
Fig. 273, which shows the vertical component acting in an opposite 
direction to the resultant external forces. 

Choosing the Sections. The fiber stresses used here are tension, 
15,000 lbs.; compression, 12,000 lbs., reduced by Gordon's formula. 

Both top and bottom chords are subjected to bending stresses 
due to the roof and ceiling joists, which come on these chords between 

the panel points. The bend¬ 
ing stresses must be added to 
the direct stresses. 

It is necessary at first to 
assume approximately what 
the direct fiber stress can be 
without exceeding the allow¬ 
able stress reduced for unsup¬ 
ported length and for the bend¬ 
ing stress. Having selected a 
Fls ' 275 ' section on the basis of this 

assumed fiber stress, the moment of inertia and the actual stress must 
be determined. If these vary materially from the allowable, a new 




JT-± 


Top Chore/ Section 
£ Sic/e P/ates 
/4 * £Ls. 4 *3 *j£ 
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STEEL CONSTRUCTION 


293 


section must be chosen and the process repeated. In this case the 
process is illustrated below. 

Top Chord. Fig. 275 shows the assumed section of top chord. The first 
step is to determine the position of neutral axis. 

Cover plates 5.25 X .19= 1.00 
Side plates 10.5 X 7.38 = 77.50 
Angles 4.96X 1.66= 8.20 
86.70 

86.70 -h 20.71 = 4.20 = Distance of neutral axis from top of cover plate. 

Moment of Inertia of Top Chord. 

lab = 5.25 X 4 2 = 84.0 
T VX f X 14 3 = 171.0 
10.5 X 3T8 2 = 106.0 

3.96 X 2 =8.0 

4.96 X 2^54 2 = 32. 

410.0 

Radius of gyration r = 4.4 
led = 5.25 X 3^69 2 X 2 = 142.5 

T V X f X 14 3 = 85.5 
1.92X2 = 3.8 

2.48 X 4~66 2 X 2 = 107.8 
339.6 

Radius of gyration r = 4.05 

The top chord between panel points may be considered as a beam 
of span equal to panel length, and fixed at the ends as regards the 
bending moment caused by the direct load. Therefore, 

M = § X i X 65 X 26 X 6T7 2 X 12 

= 64,000 inch-pounds. 

64,000X 4.2 
U ~ 401 “ 670 

212,000 _ 10,250 
‘ Sd ~ 20.7 ~ 10.920 

Since the top chord is braced laterally only at the ends and at three points 
equally distant, the unsupported length is 18 feet 6 inches. From Cambria, the 
allowable fiber stress in compression for a length of 18 feet 6 inches, and least 
radius of gyration 4.05, is found to be 11,000 lbs. reduced from 12,000 lbs. 
The above combined stress is therefore within the limit and close enough not to 
require redesign. 

Bottom Chord. The bending moment is 

M = § X i X 15 X 26 X 6T7 2 X 12 
= 14,700 pounds. 








294 


STEEL CONSTRUCTION 


Fig. 276 shows the assumed section of bottom chord. The neutral axis is 
determined as follows: 

2 X 14 Xi 5 5 X 7.38 = 64.6 
2 X 1.93X 1.44 = 5.5 

14 X f X .19 = 1.0 

71.1 



71.1 -r- 17.86 = 4.00 = Distance of center of gravity from bottom of plate. 
Moment of Inertia of Bottom Chord. 


/«6 = ^X|X 14 3 = 105.0 
8 75 X 3T38 2 = 99.6 
2 X 2.33 = 4.7 

3.86 X 2^56 2 = 25.3 
5.25 X 3^81 2 = 76.1 
310.7 


ft = 


14,700 X 4.0 
310.7 


189. 


fsd 


207,000 14,650 

14.11 (net) 14,839' 


As the bottom chord is subject only to tension, it is not necessary 
to calculate the radius of gyration or moment of inertia about axis 
c d. 

Diagonals are designed by using 15,000 lbs. tension, and choosing 
angles whose net section, taking one rivet hole out, will be sufficient 
for the stress in the member. 

Verticals are designed by assuming an allowable fiber stress based 
on the reduction of 12,000 lbs. for ratio of length to radius of gyration. 
After the section is determined, using this assumed fiber stress, it is 
necessary to see that this fiber stress is within the actual allowable 
stress for the radius of gyration of the member. 

Where two angles are used, spread the thickness of gusset plate, 
the least radius is employed, either parallel with the outstanding legs 













STEEL CONSTRUCTION 


295 


or through the axis of the gusset. Where side plates are used, as in 
this case, the radius employed should be that parallel to the outstand- 
ing legs. These angles being spread and either laced or tied with 
plates, are weakest in the direction of the axis of the truss. The 
student should follow through the different sizes given for verticals and 
diagonals, fully understanding the above explanations. 

Fig. 278 shows a detail of the connections at one top chord panel 
point; and Fig. 279, of one bottom chord panel point. It should be 


i 



noted that the rivets are in single shear, and that the side plates are 
deep enough to allow connections to be made without the use of gus¬ 
sets. 

In Fig. 267, a detail is shown of a connection suitable for a rod 
hanging, a balcony, or other member to the truss. Note that the cen¬ 
ter of rod comes at the intersection of the strain lines at the panel 
point. This should always be the case unless the chord is made speci¬ 
ally strong to resist the bending due to a connection between panel 
points. Note also that the connection is applied directly to the gusset 
plate by a pin through the clevis nut. This brings only shearing and 
bearing strains on the connection, and avoids any direct pull on the 
heads of rivets or of bolts, which should be divided wherever possible 
in such cases. 






29 G 


STEEL CONSTRUCTION 


The open holes in top chord are for securing the roof purlins to 
the truss. These purlins run directly across the top chord. 

Fig. 280 shows the detail of a truss for a boiler-house roof. This 
roof has a high monitor running down the center, which is also framed 
with steel; the detail of this frame is shown in Fig. 284. 

Fig. 284 shows a general view of the truss and monitor frame in 
position, and the roof beams framing to them. This truss was short 
enough to be riveted up at the shop and shipped whole. The monitor 



frame, however, was shipped separate from the truss, as indicated by 
the open holes for connection to truss. As this monitor frame, if 
shipped whole, would be likely to become bent and distorted, it had 
to be shipped in two parts, as indicated by the details. 

Figs. 281 and 282 show the top and bottom chord splices in the 
center panel of the truss shown in Fig. 272. Note that the point in 
top chord is specified to be planed, and therefore the rivets provided 
are sufficient for only a portion of the stress, the balance being trans¬ 
ferred by direct compression on the planed surfaces. 

















































STEEL CONSTRUCTION 


297 


PROBLEMS 

Determine ail the stresses and suitable sizes to use for a truss 
loaded as shown in Fig. 283, and resting on a brick wall at each end. 
The load consists of floor joists resting directly on the top chord; and 
a G x 4 x f-inch angle should be provided near every other panel point, 
punched for lag screws to secure to wood joists for forming a lateral 
support to truss. 

Make a complete shop detail of the above truss. 

Trussed Stringers. Figs. 285 and 286 show the two common 
forms of trussed wooden stringers. These consist of a woodpn beam, 



composed of one or more timbers, stiffened by one or two struts bearing 
on steel rods, as shown. They are used in timber-framed structures 
where it is impracticable to obtain timbers sufficiently strong to sup¬ 
port the loads. 

The trussed stringer is not a true truss, and the stresses cannot 
be accurately determined by the methods used for trusses, because the 













































298 


STEEL CONSTRUCTION 


stresses in the members depend upon the deflection of the beam as a 
member of a truss and as a beam also. The exact solution is very 


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Fig. 281. 


complicated. An approximate solution can be made as follows: 

In Fig. 285, if a load P is applied over the center strut as shown, 

then 

P ac 

Stress m ac = - X ’> 

2 ac 

Stress in ab = ? X —: and 
2 ac 

Stress in dc — P. 


If the load P is applied uniformly over the whole length of ab , 
then the stresses are approximately as follows: 









































































Fig. 280. 


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STEEL CONSTRUCTION 


299 


Load at d = § P; 

Stress in ac = T \ P x 

Direct stress in ab = T 5 g P x \ and 
ac 

Stress in dc = f P. 

The beams ad and db are however subjected to bending stress due 
to the load acting directly on the beam between the unsupported points 

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Fig. 282. 


a and d and b and d. If I is the moment of inertia of the beam, this 
bending stress can be found approximately from the formula / = 

in which y = Half the depth of the beam. 
























































































300 


STEEL CONSTRUCTION 


The bending moment may be taken as § P X ab. 

The beam must be proportioned so as to provide for the direct 


1200* Per linear foot uniformly distributed 
o ver top chord 



V 


39'- 0" 


Fig. 283. 


stress plus the stress due to bending, without exceeding the allowable 
fiber stress of the timber. 

In Fig. 28G, if a load P is-applied over each of the struts, the stress¬ 
es can be determined approximately as follows: 


Stress in ac = P X — • 



Stress in ae = P X —; and 
ac 

Stress in ec = P. 

If the load 2 P is applied uniformly over the whole length ab, 
then the stresses are approximately as follows: 

The load at e and / can be taken approximately as | P; then 



Stress in ac 


Direct stress in ae = £ P X —; and 
ac 

Stress in ec = ^ P. 


The portions ac, ef, and fb are subjected to bending stresses as 


p 







c 


Fig. 285. 


before; and if I is the moment of inertia of the beam, the bending 


stress in ae = in which ij = \ Depth of the beam; the bending M 


may be taken as JPX ab . The beam must be proportioned so that 


c to c 





















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302 


STEEL CONSTRUCTION 


the combined bending and direct stress shall not exceed the safe fiber 
stress for the timber. 

Owing to the fact that the actual distribution of stress in trussed 
stringers is uncertain, and the methods of determining these stresses 
only approximate, a factor of safety of not less than 5 should be used. 

The detail of the connection of the rods with the end of the beam 



c d 


Fig. 286. 

is shown in Fig. 287. Sometimes a single rod going between a hori¬ 
zontal beam made of two timbers, is used; and sometimes where two 
rods are used, these are placed outside of the timber. A detail which 
will avoid boring through the timber is preferable. The plate at the 
end must be large enough to distribute the stress without exceeding the 



safe compression value of the timber used; for hard pine, this should 
be 1,000 pounds per square inch. The plate should be thick enough 
to provide for the shearing stress on the metal, and the bending stress 
induced by the pull of the rod on the unsupported portion of the plate. 

It is important to have the center lines of the members intersect 
at the center of the bearing, as otherwise considerable additional bend¬ 
ing stress will be caused, owing to the eccentricity. 
















INDEX 


Page 

Abbreviations used in steel construction. 181 

Allowable values for buildings. 253 

Anchors. 97 

Angles..12, 15 

Arches. 8 

floor. 62 

roof. 62 

Batten plates. 185 

Beam plates.. 96 

Beams. 8 

lateral deflection of. 28 

problems on. 101 

Beams and girders. 91 

loads 

determination of. 91 

distribution of. 92 

Bearing partitions. 6 

Bearing power of soils, improvement of. 151 

Bearing value of rivets, determination of. 196 

Bracing trusses. 122 

Building laws and specifications. 44 

Caisson foundations.*. 147 

Cantilever foundations. 156 

Cap details. 227 

Cast-iron columns. 119 

Choosing sections. 292 

Clevis nuts. 183 

Coefficient of strength. 38 

Column bases. 126 

Column capacity, diagram of. 116 

Column caps. 126 

Column connections, effect of. 108 

Column coverings. 86 

Column details. 226 

base.. • • . 226 

cap.. • 227 

illustrations of. 228 

shaft. 228 

Column sections. 112 

calculation of. 113 

selection of. 112 











































304 


INDEX 


Page 

Column splices. 126 

Columns. 105 

cast-iron. 119 

concrete and steel. 120 

position of. .. 52 

practical considerations in. 119 

shapes used. 106 

Concrete and steel columns. 120 

Concrete-steel floor and roof arches. 66 

Concrete walls. 6 

Connections, standard form of. 139 

Conventional signs in shop drawings. 192 

Corrosion of steel. 86 

Corrugated iron. 15 

Crippling of web. 255 

Curtain walls. 4 

Cutting'off flange plate. 261 

Deflection. 25 

Detail 

effect of changes in. 144 

illustrations of. 203 

scales used in. 183 

use of in work;. 144 

Detail shop drawings, use of.138, 187 

Detailing from framing plan. 212 

Determination of loads on trusses. 124 

Drawings and specifications, interpretation of. 137 

Drift pins. 182 

Economical depth of web. 254 

Enclosing walls. 3 

concrete. 6 

curtain. 4 

load-bearing. .. 3 

metal. 5 

self-supporting. 4 

Engineer’s relation to architect. 136 

Equal radii of gyration . 39 

Estimating cost of steel work. 142 

Eye bars. 184 

Factor of safety. 49 

Fireproof materials. 61 

Fire-resisting materials. 61 

Fire-resisting woods. 88 

Fitting-up bolts. 182 

Flange plate, cutting off. 261 

Flange rivets, spacing of. . . .. 264 

Flange splices. 266 

Flanges, proportioning. 252 





















































INDEX 


395 


Page 

Flanges and web, functions of. 251 

Floor arches. 62 

concrete-steel. 66 

terra cotta. 62 

tests of. 75 

Floors. 8 

Forked eye rods. 184 

Foundations. . . .. 145 

caisson. 147 

cantilever. 156 

fundamental principles of. 148 

grillage. 152 

pile. 147 

spread. 145 

Framing 

column bases. 126 

column caps. 126 

column splices . 126 

connections. 126 

details of. 126 

inspection. 135 

relation to other work. 134 

roof details. 133 

Girders. 8 

shop details of..271 

Grillage foundations.. . .. 152 

Guastavino arch. 66 

High building construction. . .. 161 

effect on foundations. 162 

effect of wind pressure. 163 

origin of types. 161 

types in use. 162 

wind bracing. 166 

Improvement of bearing power of soils. 151 

Interior columns. 6 

Joints, strength of. 195 

Lacing.... 185 

Lag screws. 182 

Lateral deflection.*.. • 21 

of beams. 28 

Lintels. 94 

Load-bearing walls. 3 

Lomas nuts. 183 

Loop eye rods.... • 183 

Measurements,, completeness of. 284 

Metal walls. 5 

Mill or shop invoices. 142 

Mill building columns. 241 




















































INDEX 


306 


Mill building construction. 

Paints for protection of steel.... 

Partitions. 

tests of. 

Pile foundations.. 

Pilot nuts... 

Plain rod. 

Plate rfuts.> . ... 

Plates...*. 

Proportioning flanges. 

Proportioning the web. 

Radius of gyration... 

Reduction in live load on columns, girders, and foundations 

Retaining walls.. 

Right-hand threads. 

Rivet holes. 

Riveted girders. 

Rivets and riveting. 

Rods and bars. 

Roof.. 

Roof arches. 

concrete-steel. 

terra cotta.. 

tests of.. . .. 

Roof details.. 

Safe loads, table. 

Safe loads above spans limited by deflection, rule for. 

Scales used in details. 

Section modulus. 

Sections, use of.... 

Selectionof system.. 

Self-supporting walls. 

Separators... 

Shaft details..-. 

Shearing.value of rivets, determination of ... ... 

Sheath piling. 

Shop details, illustrations of. 

Shop drawings. 

relation of.i. 

Shop practice. 

Sleeve nuts. 

Spacing of beams... 

Spacing of flange rivets.!. 

Spandrel beams.. 

Split nuts... 

Spread foundations. 

Standard connections.. 

Standard threads. . 


Page 
. 172 
. 87 

. 82 
. ,84 
. 147 
. 182 
. 184 
. 183 
13, 15 
. 252 
. 254 
. 35 

. 48 

. 159 
. 184 
. 190 
. 251 
. 191 
. 15 

8 

. 62 
. 66 
. 62 
. 75 

. 133 
. 18 
. 24 

. 189 
. 35 

. 14 

. 79 

4 

. 97 

. 228 
. 195 
. 160 
. 286 
. 186 
. 138 
. 138 
. 183 
. 24 

. 264 

5 

183 
145 
199 

184 























































INDEX 


307 


Standards in detailing trusses. 2 S 9 

Steel 

characteristics of shapes. 22 

corrosion of. ^ 

method of rolling. 2 () 

rules for ordering.. 25 

use of handbooks on. g 

Steel frame.. 

Steel tables, use of. 2 o 

Stiffeners 

slze of . 260 

use of. 255 

Strength of joints. 295 

Stress 

in diagonals. 292 

direction of. 291 

in verticals. 291 

Structural elements of a building. 3 

bearing partitions. g 

enclosing walls. 3 

floors. g 

foundations. 245 

roof. g 

Tables 

allowable unit-stresses for steel and cast-iron, as specified by building 

laws of different cities... 45 

bearing power of soils. 251 

breaking loads of hollow tile arches. 79 

brick-bearing walls, thickness in inches of. 46 

coefficients for deflection in inches for Cambria shapes used as beams 

subjected to safe loads uniformly distributed. 27 

live-loads in different classes cf buildings as specified by building laws 

of different cities. 44 

properties of Carnegie corrugated plates. 32 

properties of Carnegie trough plates. 32 

properties of channels. 34 

properties of I-beams. 30 

properties of standard and special angles. 36, 40 

reduction in values of allowable fibre stress and safe loads for shapes 

used as beams due to lateral flexure. 28 

roof pressures. 124 

safe loads uniformly distributed for hollow-tile arches .. 81 

safe loads uniformly distributed for standard and special I-beams and 

channels, in tons of 2,000 lbs. 18 

spacing of standard I-beams for uniform load of 100 lbs. per sq. ft. 22 

transverse strength of stone, brick, and concrete. 46 

weights of hollow-tile arches and fireproof materials.. 80 

weights of materials in floor and roof construction. 82 














































308 


INDEX 


Tables Page 

weights of various substances and materials of construction. 93 

Tees.. 15 

Terra cotta floor and roof arches.. 62 

Tests of partitions... 84 

Tie rods.60, 183 

Trussed stringers. 297 

Trusses. 122 

bracing. 122 

design of. 123 

determination of loads. 124 

practical considerations. 123 

selection of type. 122 

Turnbuckles. 183 

Underpinning shoring. 160 

Upset rods. 184 

Vertical deflection. 21 

Walls, enclosing. 3 

Web 

crippling of.255 

economical depth of. 254 

proportioning. 254 

Web splices. 268 

Wind pressure. 48 

Zees. 15 

































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AMERICAN SCHOOL OF CORRESPONDENCE, CHICAGO 
































































































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